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Saturday, February 28, 2009
Pentax Service Manuals
Friday, February 27, 2009
DA* 55/1.4 Vs FA 50/1.4 - A Measurebating Shootout
Here is a very interesting shootout on the two "similar" Pentax lenses of different generations with some unique and effective measurebations:-
http://www.informatik.uni-bremen.de/foto-ag/DA55/DA55.html
The test report is concisely and clearly written and all the findings and observations are self-explanatory. Still, I extract some of the more interesting sentences below which I would add the comments of mine:-
"Disclaimer: This is a test by a layman, who does not really know what he is doing."
This guy is surely not a layman! His tests are cleverly and carefully designed. They are all simple and effective. I have rarely seen people who could do such excellent works at that high level! He even measured bokeh and has been able to qualify the difference in an easy way! He also plotted the spatial frequency charts which give us a general idea on the MTF response and changes from low to high spatial frequencies! "Layman"? :-o Well, he is just an humble guy who does not like to say loudly (unlikely me ;-D). Indeed, I would say he is just an excellent "measurbator"! (Thumb Up)
"AF Speed: The big disadvantage of the DA55 is that it is much slower compared to the FA50 in AF speed (measured using Audacity). The DA55 is about 3 times slower than the FA! I am wondering why this is so and what Pentax has to say about it. Isn't it a confession of failure that an almost 20 year old lens focusses so much faster?"
Oh, yes. Why's that? The SDM was found to be slower, but now this time it is even *much* slower!!? It is not about the travel and throw of the mechanical movement range of the focusing part of the lens, nor it is about the weight of the lens element to be focused, as it is found that:-
"Throw of the focussing ring:
FA85: ca. 90 degrees (superfast AF)
DA55: ca. 110 degrees (slow AF)
FA50: ca. 120 degrees (fast AF)"
So, the FA 50 has longer travel but the FA* 85 undoubtedly has much heavier glass, but neither of them is as slow as the DA* 55. Now, the culprit? IMO it *must* be the SDM, which is inferior in terms of speed (weak torque?), which is even much slower than the old type Pentax body-driven screw-type AF! (but why?)
"Bokeh:
Circle of confusion in the background:
(below the brightness across the ring is shown)"
He simply plotted the lightness response curve and it shows the "bright ring" bokeh which quite some Pentaxians have been puzzled about (provided that they know it)! Amazing! Well Done, Mr. ! You're my Hero!
And, his series of bokeh test shots are well thought and well done. More importantly, they are simple enough but yet clearly presented.
In the end, I don't think the DA* 55 is anything that really worth to invest, with its three time higher price tag than the old FA 50. Yes, it is somehow sharper from corner to corner when the lens is wide opened. Except this, there is no clear advantage optically and in image quality. But what's the real point for a portrait lens to have corner to corner sharpness when wide opened?
Furthermore, it is bulkier and heavier and subjectively I regard the outlook of the lens is Ugly, and so do all the DA Star lenses. In contrast, the FA Star lenses are beautiful (Sad). And yes, it is weather sealed and has the USM. But so what? Especially considered that the USM focuses rather sloooowly despite it is *almost* silent (but not totally). And, as the tester said, it is really ridiculous to have a lens made almost 20 years later, it is yet focusing far slower than a lens made with the technology of late 80s! OMG!
http://www.informatik.uni-bremen.de/foto-ag/DA55/DA55.html
The test report is concisely and clearly written and all the findings and observations are self-explanatory. Still, I extract some of the more interesting sentences below which I would add the comments of mine:-
"Disclaimer: This is a test by a layman, who does not really know what he is doing."
This guy is surely not a layman! His tests are cleverly and carefully designed. They are all simple and effective. I have rarely seen people who could do such excellent works at that high level! He even measured bokeh and has been able to qualify the difference in an easy way! He also plotted the spatial frequency charts which give us a general idea on the MTF response and changes from low to high spatial frequencies! "Layman"? :-o Well, he is just an humble guy who does not like to say loudly (unlikely me ;-D). Indeed, I would say he is just an excellent "measurbator"! (Thumb Up)
"AF Speed: The big disadvantage of the DA55 is that it is much slower compared to the FA50 in AF speed (measured using Audacity). The DA55 is about 3 times slower than the FA! I am wondering why this is so and what Pentax has to say about it. Isn't it a confession of failure that an almost 20 year old lens focusses so much faster?"
Oh, yes. Why's that? The SDM was found to be slower, but now this time it is even *much* slower!!? It is not about the travel and throw of the mechanical movement range of the focusing part of the lens, nor it is about the weight of the lens element to be focused, as it is found that:-
"Throw of the focussing ring:
FA85: ca. 90 degrees (superfast AF)
DA55: ca. 110 degrees (slow AF)
FA50: ca. 120 degrees (fast AF)"
So, the FA 50 has longer travel but the FA* 85 undoubtedly has much heavier glass, but neither of them is as slow as the DA* 55. Now, the culprit? IMO it *must* be the SDM, which is inferior in terms of speed (weak torque?), which is even much slower than the old type Pentax body-driven screw-type AF! (but why?)
"Bokeh:
Circle of confusion in the background:
(below the brightness across the ring is shown)"
He simply plotted the lightness response curve and it shows the "bright ring" bokeh which quite some Pentaxians have been puzzled about (provided that they know it)! Amazing! Well Done, Mr. ! You're my Hero!
And, his series of bokeh test shots are well thought and well done. More importantly, they are simple enough but yet clearly presented.
In the end, I don't think the DA* 55 is anything that really worth to invest, with its three time higher price tag than the old FA 50. Yes, it is somehow sharper from corner to corner when the lens is wide opened. Except this, there is no clear advantage optically and in image quality. But what's the real point for a portrait lens to have corner to corner sharpness when wide opened?
Furthermore, it is bulkier and heavier and subjectively I regard the outlook of the lens is Ugly, and so do all the DA Star lenses. In contrast, the FA Star lenses are beautiful (Sad). And yes, it is weather sealed and has the USM. But so what? Especially considered that the USM focuses rather sloooowly despite it is *almost* silent (but not totally). And, as the tester said, it is really ridiculous to have a lens made almost 20 years later, it is yet focusing far slower than a lens made with the technology of late 80s! OMG!
Thursday, February 26, 2009
SDM Reliability Issue
I have seen yet again another Pentax user reported failure of the Supersonic Drive Motor (SDM) of his SDM lens:
http://forum.pentaxfans.net/showthread.php?t=73981
(Text in Traditional Chinese, use Babelfish or Google Translate to translate if needed)
He said that he bought his lens in August last year and has used his lens only for 3 times!
In fact, the SDMs of the DA* 16-50 and the DA* 50-135 seem to be prone to fail. A quick search on major Pentax gear forums will reveal many reports on these, for example:-
http://search.dpreview.com/?forumid=1036&scope=Forums&sort=date&q=sdm+issue
For average Pentax users, the reason(s) for why these two lenses are having more failure reports are actually unknown. It maybe just that they are the first generation of the SDM lenses and the design was not yet mature. On the other hand, it could be that these two lens models have been sold more in number (since they are the oldest and thus the marketing period is longer). But one thing seems to be almost certain, that is, there exists some quality or design issues for the SDM used in these lenses so that the durability and reliabiity of this type of AF motor as used by Pentax are in question.
http://forum.pentaxfans.net/showthread.php?t=73981
(Text in Traditional Chinese, use Babelfish or Google Translate to translate if needed)
He said that he bought his lens in August last year and has used his lens only for 3 times!
In fact, the SDMs of the DA* 16-50 and the DA* 50-135 seem to be prone to fail. A quick search on major Pentax gear forums will reveal many reports on these, for example:-
http://search.dpreview.com/?forumid=1036&scope=Forums&sort=date&q=sdm+issue
For average Pentax users, the reason(s) for why these two lenses are having more failure reports are actually unknown. It maybe just that they are the first generation of the SDM lenses and the design was not yet mature. On the other hand, it could be that these two lens models have been sold more in number (since they are the oldest and thus the marketing period is longer). But one thing seems to be almost certain, that is, there exists some quality or design issues for the SDM used in these lenses so that the durability and reliabiity of this type of AF motor as used by Pentax are in question.
Thursday, February 19, 2009
DA 18-250 Discontinued
It's Official! The DA 18-250 has been discontinued:-
http://www.pentax.jp/japan/imaging/digital/lens/index35_others.html
(Page Text in Japanese)
So, there is yet another lens which has been discontinued by Pentax recently, following the FA 35/2 lens, which has just been discontinued just earlier (it is not as official, though).
But unlike the FA 35/2 lens, the DA 18-250 is just a very new lens, which was only introduced in 2007. It is widely believed that the DA 18-250 is originally or mostly manufactured by Tamron as the specifications of the lens look almost identical to the Tamron counterpart.
Well, there are two possibilities for the dismissal of the DA 18-250 "Superzoom": 1. There is not sufficient market demand to substantiate its production; 2. There will be a new replacement model to come.
As for the first guessed reason, the chance would be high. It is because the DA 18-250 is selling relatively much more expensive than the Tamron and there are just already too many choices for such superzooms, either from Tamron, Sigma or even from Tokina "themself" (as Tokina is also owned by Hoya) but all of which are much cheaper. Moreover, from viewing the market share of Pentax DSLRs by now, I bet even 3rd party lens makers will have hesitation to produce lenses in Pentax mount, frankly.
As for if there will be a new replacement model (might also be a rebadged Tamron if so, as Tamron do have the new models - but why don't Pentax find Tokina?), we shall know it very soon by the PMA.
Well, there is an (might be crazy :-)) idea that comes across my mind that might save Pentax: It is, Pentax to launch Pentax lenses in other popular mounts (in fact just C and N now) and to be a "3rd party" lens manufacturer, like what "Carl Zeiss" to market their ZF, ZE and ZK "Carl Zeiss" lenses (actually by Sony, it is believed). By that time, Pentax could have more money to compete and users of other big brands could try and would know how good (or bad, anyway) Pentax optics are, when the Pentax lenses are mounted onto their bodies. And I do believe that the current adverse marketing and financial situation as faced by Pentax (and actually Hoya) could be changed and improved if Pentax / Hoya can sell far more lenses and earn some money, unlike now they only know how to "streamline" their lens lineup, which is of no doubt is even far more smaller than the current Sigma's.
If it is really feasible (technically, legally and politically) and it comes true, I am sure that Pentax can and will survive and undoubtedly they will have more fundings (and thus resources) to make more and better DSLR bodies, with the new money gained.
My experiences are that my Pentax lenses perform much better on my EOS 5D than any of my Pentax DSLRs, even for some digital lenses that could produce "strange" results when they are used on Pentax DSLRs (my DFA 100 lens is a good example here), why not go the way?
http://www.pentax.jp/japan/imaging/digital/lens/index35_others.html
(Page Text in Japanese)
So, there is yet another lens which has been discontinued by Pentax recently, following the FA 35/2 lens, which has just been discontinued just earlier (it is not as official, though).
But unlike the FA 35/2 lens, the DA 18-250 is just a very new lens, which was only introduced in 2007. It is widely believed that the DA 18-250 is originally or mostly manufactured by Tamron as the specifications of the lens look almost identical to the Tamron counterpart.
Well, there are two possibilities for the dismissal of the DA 18-250 "Superzoom": 1. There is not sufficient market demand to substantiate its production; 2. There will be a new replacement model to come.
As for the first guessed reason, the chance would be high. It is because the DA 18-250 is selling relatively much more expensive than the Tamron and there are just already too many choices for such superzooms, either from Tamron, Sigma or even from Tokina "themself" (as Tokina is also owned by Hoya) but all of which are much cheaper. Moreover, from viewing the market share of Pentax DSLRs by now, I bet even 3rd party lens makers will have hesitation to produce lenses in Pentax mount, frankly.
As for if there will be a new replacement model (might also be a rebadged Tamron if so, as Tamron do have the new models - but why don't Pentax find Tokina?), we shall know it very soon by the PMA.
Well, there is an (might be crazy :-)) idea that comes across my mind that might save Pentax: It is, Pentax to launch Pentax lenses in other popular mounts (in fact just C and N now) and to be a "3rd party" lens manufacturer, like what "Carl Zeiss" to market their ZF, ZE and ZK "Carl Zeiss" lenses (actually by Sony, it is believed). By that time, Pentax could have more money to compete and users of other big brands could try and would know how good (or bad, anyway) Pentax optics are, when the Pentax lenses are mounted onto their bodies. And I do believe that the current adverse marketing and financial situation as faced by Pentax (and actually Hoya) could be changed and improved if Pentax / Hoya can sell far more lenses and earn some money, unlike now they only know how to "streamline" their lens lineup, which is of no doubt is even far more smaller than the current Sigma's.
If it is really feasible (technically, legally and politically) and it comes true, I am sure that Pentax can and will survive and undoubtedly they will have more fundings (and thus resources) to make more and better DSLR bodies, with the new money gained.
My experiences are that my Pentax lenses perform much better on my EOS 5D than any of my Pentax DSLRs, even for some digital lenses that could produce "strange" results when they are used on Pentax DSLRs (my DFA 100 lens is a good example here), why not go the way?
Sunday, February 15, 2009
GX-20 Vs K20D - Fully Compared
Here is an earlier Chinese article in which head-to-head comparisons of the twin-born DSLRs, the Samsung GX-20 and the Pentax K20D, were made:-
Part 1: Comparisons on designs and specs, appearances, general operations and features (including the different menu designs), some timing figures and SR (Shake Reduction) tests, the similarities and differences:-
http://tech.163.com/digi/08/0429/01/4ALLBET5001628C0.html
(Text in Simplified Chinese, use Babelfish or Google Translate if needed)
It would be interesting to note that the two cameras' operation interfaces/menus do have quite some differences. The Samsung's one seems to be better IMO and with more detailed information provided, e.g., for the LiveView function, it displays the (selected) exposure figures whilst there is none for the K20D, see here for what they have shown.
But sometimes the K20D will yet give the user more options, e.g., the K20D has the proprietary PEF (compressed) RAW file format and the "200% Dynamic Range" option (1EV more, theoretically), which the GX-20 lacks.
Well, I think you will not be satisfied just with the above! So, they wrote also the second part of their shootout, for some additional measur(e)bations:-
http://tech.163.com/digi/08/0430/03/4AODO93C001628C0.html
(Text in Simplified Chinese, use Babelfish or Google Translate if needed)
I would like to highlight some of the more important points as follows (and some remarks of mine as well):-
1. In RAW (DNG format), the GX-20 gave slightly higher resolution figures and the differences are particularly more obvious at wider aperture than f/5.6.
2. In JPEG, the K20D clearly gave higher resolution. But since the testers used the Imatest for the test (MTF set at 50% as told), higher figures does not necessary mean to be good absolutely, as more aliasing could occur. In contrast, if the hardware (sensor and the Anti-Aliasing filter) and/or the software did more anti-aliasing, the resolution could be affected. This explains why the JPEG resolution figures could be higher than the RAW figures for incident.
3. The default "Standard" colour mode of the GX-20 is more vivid than the default "Natural" mode of the K20D.
4. Using both standard colour mode, the Auto White Balance errors of the GX-20 were yet less than what the K20D produced (i.e., the GX-20's AWB was more accurate), despite that the GX-20 have already set to produce more exaggerated colours by default. Well, I think I should say a "Well done" here to Samsung for this! Particularly, the K20D produces far more errors for the darkest shadow.
5. The colour tendency of the Samsung and the Pentax are different too. Pentax gives warmer overall tone particular for the green whereas the Samsung could be colder for the green and overall more *neutral* (against the "yellowish" tone of the K20D).
6. The GX-20 default noise reduction is more aggressive and thus it produces smoother pictures throughout the whole ISO range whereas the K20D pictures by default are more noisy, but retain better details. Noise reduction on the "Strong" setting were also tested. So, you can't get the best of both worlds? Yes. So, here is another good and solid reason why we do need a Full Frame DSLR!
7. More sample "reallife" shots are posted for both cameras and different lenses were also tested, including a Rikenon.
So, go read and enjoy the articles yourself, but please don't measurebate and pixel-peeping too much! ;-) (But of course its all up to you then!)
Part 1: Comparisons on designs and specs, appearances, general operations and features (including the different menu designs), some timing figures and SR (Shake Reduction) tests, the similarities and differences:-
http://tech.163.com/digi/08/0429/01/4ALLBET5001628C0.html
(Text in Simplified Chinese, use Babelfish or Google Translate if needed)
It would be interesting to note that the two cameras' operation interfaces/menus do have quite some differences. The Samsung's one seems to be better IMO and with more detailed information provided, e.g., for the LiveView function, it displays the (selected) exposure figures whilst there is none for the K20D, see here for what they have shown.
But sometimes the K20D will yet give the user more options, e.g., the K20D has the proprietary PEF (compressed) RAW file format and the "200% Dynamic Range" option (1EV more, theoretically), which the GX-20 lacks.
Well, I think you will not be satisfied just with the above! So, they wrote also the second part of their shootout, for some additional measur(e)bations:-
http://tech.163.com/digi/08/0430/03/4AODO93C001628C0.html
(Text in Simplified Chinese, use Babelfish or Google Translate if needed)
I would like to highlight some of the more important points as follows (and some remarks of mine as well):-
1. In RAW (DNG format), the GX-20 gave slightly higher resolution figures and the differences are particularly more obvious at wider aperture than f/5.6.
2. In JPEG, the K20D clearly gave higher resolution. But since the testers used the Imatest for the test (MTF set at 50% as told), higher figures does not necessary mean to be good absolutely, as more aliasing could occur. In contrast, if the hardware (sensor and the Anti-Aliasing filter) and/or the software did more anti-aliasing, the resolution could be affected. This explains why the JPEG resolution figures could be higher than the RAW figures for incident.
3. The default "Standard" colour mode of the GX-20 is more vivid than the default "Natural" mode of the K20D.
4. Using both standard colour mode, the Auto White Balance errors of the GX-20 were yet less than what the K20D produced (i.e., the GX-20's AWB was more accurate), despite that the GX-20 have already set to produce more exaggerated colours by default. Well, I think I should say a "Well done" here to Samsung for this! Particularly, the K20D produces far more errors for the darkest shadow.
5. The colour tendency of the Samsung and the Pentax are different too. Pentax gives warmer overall tone particular for the green whereas the Samsung could be colder for the green and overall more *neutral* (against the "yellowish" tone of the K20D).
6. The GX-20 default noise reduction is more aggressive and thus it produces smoother pictures throughout the whole ISO range whereas the K20D pictures by default are more noisy, but retain better details. Noise reduction on the "Strong" setting were also tested. So, you can't get the best of both worlds? Yes. So, here is another good and solid reason why we do need a Full Frame DSLR!
7. More sample "reallife" shots are posted for both cameras and different lenses were also tested, including a Rikenon.
So, go read and enjoy the articles yourself, but please don't measurebate and pixel-peeping too much! ;-) (But of course its all up to you then!)
Thursday, February 12, 2009
FA 35 F2 Discontinued
B&H have marked the FA 35 F2 lens as discontinued in their website:-
http://www.bhphotovideo.com/c/product/180121-USA/Pentax_22190_Wide_Angle_35mm_f_2_0.html
As a verification to the update, I have checked the official Pentax Imaging website, it is also found that the FA 35 has been removed from the lens section:-
http://www.pentaximaging.com/camera-lenses/#7
On the other hand, official Pentax Japanese website still lists the FA 35. But I bet it will not last longer, or it is just that the website has not yet been updated.
It is rather pity that this lens is discontinued, it is the indeed the best value lens in the current Pentax lens lineup with a very high price-performance ratio. It has very good optical quality but yet it is not expensive. Besides, I like much the favourable colour response of the lens and so do almost all Pentax FA lenses, in contrast to the unfavourable colour response of some of those DA/DFA "digital" Pentax lenses. The even strange thing is that when I use some of those "unfavourable" lenses on my 5D, the outcome looks (much) better again! (The body corrects the "errors"?)
While Nikon have just announced their latest 35/1.8 DX and the rationale why they have made it, Pentax, the one who have been emphasizing on an APS-C system, now discontinue a popular lens for their APS-C system. In fact, the FA35 is very practical and useful and just act like a 50mm standard lens on a 1.5X body (as Nikon have said this). Providing that Pentax have a better market share of the 1.5X bodies, the demand for this "standard" prime should be large. And, despite the FA 35 is priced similar to the upcoming new Nikkor DX 35, I am sure that the FA 35 is better built and at least it has the distance scale!
I bet the reasons for Pentax (have) to discontinue the FA 35 is not owing to that the FA 35/2 is not useful and not good on their APS-C bodies, but only that they have to choose to discontinue some of their lenses for many unfavourable factors/facts which they are thinking about, say: (lens) production factilities at Japan closed, shrinking of market share of their DSLR bodies (so market demand for their lenses must be shrinking too), "conflicts" with the DA 35/2.8 Macro (but really?) and so on..
With the discontinuation of the FA 35, this marks nearly an end to the Pentax excellent line of FA lenses. Now only the 3 FA Limited lenses are left in the Pentax's lineup, which probably are now made in the Pentax factory at Vietnam instead of anywhere at Japan, but how long will they last? (And, the new FA Limited could be different in Image Quality than the older/oldest ones, see this.)
Anyway, if you want to buy the FA 35/2, do hurry up! Grab one until stock lasts and get it anywhere you can find, e.g., Adorama still lists it (but you have to check if they really carries it, anyway). I did the same in 2004 when the FA 28 discontinued and got one from the last lots of stock.
http://www.bhphotovideo.com/c/product/180121-USA/Pentax_22190_Wide_Angle_35mm_f_2_0.html
As a verification to the update, I have checked the official Pentax Imaging website, it is also found that the FA 35 has been removed from the lens section:-
http://www.pentaximaging.com/camera-lenses/#7
On the other hand, official Pentax Japanese website still lists the FA 35. But I bet it will not last longer, or it is just that the website has not yet been updated.
It is rather pity that this lens is discontinued, it is the indeed the best value lens in the current Pentax lens lineup with a very high price-performance ratio. It has very good optical quality but yet it is not expensive. Besides, I like much the favourable colour response of the lens and so do almost all Pentax FA lenses, in contrast to the unfavourable colour response of some of those DA/DFA "digital" Pentax lenses. The even strange thing is that when I use some of those "unfavourable" lenses on my 5D, the outcome looks (much) better again! (The body corrects the "errors"?)
While Nikon have just announced their latest 35/1.8 DX and the rationale why they have made it, Pentax, the one who have been emphasizing on an APS-C system, now discontinue a popular lens for their APS-C system. In fact, the FA35 is very practical and useful and just act like a 50mm standard lens on a 1.5X body (as Nikon have said this). Providing that Pentax have a better market share of the 1.5X bodies, the demand for this "standard" prime should be large. And, despite the FA 35 is priced similar to the upcoming new Nikkor DX 35, I am sure that the FA 35 is better built and at least it has the distance scale!
I bet the reasons for Pentax (have) to discontinue the FA 35 is not owing to that the FA 35/2 is not useful and not good on their APS-C bodies, but only that they have to choose to discontinue some of their lenses for many unfavourable factors/facts which they are thinking about, say: (lens) production factilities at Japan closed, shrinking of market share of their DSLR bodies (so market demand for their lenses must be shrinking too), "conflicts" with the DA 35/2.8 Macro (but really?) and so on..
With the discontinuation of the FA 35, this marks nearly an end to the Pentax excellent line of FA lenses. Now only the 3 FA Limited lenses are left in the Pentax's lineup, which probably are now made in the Pentax factory at Vietnam instead of anywhere at Japan, but how long will they last? (And, the new FA Limited could be different in Image Quality than the older/oldest ones, see this.)
Anyway, if you want to buy the FA 35/2, do hurry up! Grab one until stock lasts and get it anywhere you can find, e.g., Adorama still lists it (but you have to check if they really carries it, anyway). I did the same in 2004 when the FA 28 discontinued and got one from the last lots of stock.
Friday, February 06, 2009
Exploded View Diagrams of the K20D and *ist DL
PentaxForums new member "odgc8" posted the Exploded View Diagrams of the K20D and the *ist DL respectively some days before:-
http://www.pentaxforums.com/forums/pentax-dslr-discussion/48973-k20d-exploded-view-parts.html
http://www.pentaxforums.com/forums/pentax-dslr-discussion/48910-pentax-ist-dl-exploded-view.html
The direct links are as follows:-
[Exploded View Diagram of the K20D] [Exploded View Diagram of the *ist DL]
For those Pentaxians who are interested, just download the pdf files and have a look. And, for those who find the diagram really useful and want to do something to your cameras, I still have a typical humble advice and actually warning to you: Be *careful* and do anything at your own risk. And, YOU are the ONE who *should* and are *knowing* what you are doing!
Just in case if you have no confidence, just don't do it.
Well, when I am saying "do" this and do "that" but actually do you know "doing what" and "what" purposes are the users for doing that? ;-) I dunno, only those users themselves would know! But possibly it can be this:-
http://forum.manualfocus.org/viewtopic.php?id=11949
The above modification looks quite meaningful.. (provided that you have the *need*!)
Good luck and Happy Camera Hacking! (if you wish and dare!)
http://www.pentaxforums.com/forums/pentax-dslr-discussion/48973-k20d-exploded-view-parts.html
http://www.pentaxforums.com/forums/pentax-dslr-discussion/48910-pentax-ist-dl-exploded-view.html
The direct links are as follows:-
[Exploded View Diagram of the K20D] [Exploded View Diagram of the *ist DL]
For those Pentaxians who are interested, just download the pdf files and have a look. And, for those who find the diagram really useful and want to do something to your cameras, I still have a typical humble advice and actually warning to you: Be *careful* and do anything at your own risk. And, YOU are the ONE who *should* and are *knowing* what you are doing!
Just in case if you have no confidence, just don't do it.
Well, when I am saying "do" this and do "that" but actually do you know "doing what" and "what" purposes are the users for doing that? ;-) I dunno, only those users themselves would know! But possibly it can be this:-
http://forum.manualfocus.org/viewtopic.php?id=11949
The above modification looks quite meaningful.. (provided that you have the *need*!)
Good luck and Happy Camera Hacking! (if you wish and dare!)
Saturday, January 31, 2009
Problematic DPR "Reviews" (Esp. Recent Ones)
As I have always said, camera gear "review", by its name, is just a kind of unprofessional assessment on camera gear, which is more or less consisted of many personal opinions and comments made by individual writer rather than more on scientific measurements. For professional ones with proper measurements, which should strictly follow those well-established International Standards and/or Industrial Standards such as ISO, IEC EN, ANSI, ASTM and etc., for the testing procedures and then for the verifications of the obtained results, they are called "Lab Tests" or "Bench Tests", NOT "Reviews".
But then about ten years ago, there came the DPReview (DPR) website, which the site owner Phil Askey used to call his user reports on digital cameras and gear as "reviews". Those reports of him were just summaries of his personal findings (based on some very simple "measurements" or even not), comments and opinions about the gear: no more, no less. Since at that time, there was not much useful information on the Internet and ditto for many of those printed magazines, in which most of the "test" reports are almost useless, the DPR became more and more popular and "large". A good example for those limited information age of the Internet is no better to quote the Steve's Digicams which produced really crappy useless "reviews" (you'd better download an official user manual from an official site and could get more info about the cameras!) could still earn a living! Nowadays, the term "review" has now been widely accepted and has a generalised meaning for any gear test or comment report, regardless of how they were done, i.e., anyone can write a "review", from a novice who knows almost nothing versus a real expert who has been working in the industry for years and has acquired different professional qualifications in the relevant fields and areas of the industry.
So, let me go back to the topic. What makes me to write this blog article immediately is that I can see the quality, usefulness and creditability of those published camera reviews by the DPR are declining. But yet I know that the general public of the Internet *still* trust too much the DPR (well, it is just a tradition by now). The general audience, whom are huge for those who read their site, just rely too heavily on their reports. For all these reasons, I opt to write here something to share my observations and thoughts with a sole intention to draw the attention of any of those internet readers for the flaws and problems of those DPR reviews (more so recently, and also the upcoming reviews, very likely). In fact, I can see that DPR and Phil Askey have spent no more new effort in improving the quality and standard of their reviews with better contents. Instead, Phil's crew and staff who called themselves as "technical writers", are just knowing to follow strictly the old report template that has been used by their boss for long, which IMO is just rather outdated by today's standards.
Now, let's go on to see why the DPR reviews are now so problematic. I will elaborate more in details with *some* examples:-
1. Inconsistent Judgements/Yardsticks
Since Uncle Phil sold his DPR site to Amazon and became the Overlord of the site, he employed a team of crew of his own so that Phil could have more time to enjoy more of his life from his hard earned money, which should not be a small sum as Amazon is just a very large company! Well, just think if you had the money, you would want more time, so that you could spend your money! Right? :-)
But after that, all the DPR reviews were written by different person(s), sometimes one, sometimes two, sometimes three and sometimes four. Phil sometimes participated with his name appeared as one of the reviewers, but not often. But then what's the (real) problem? With different combinations of different persons as the reviewers, their viewpoints, judgements or simply prejudgements could be very different, even though it seems that there is a well-established "system, which is just more or less a document template for the review report format.
Nevertheless, on the other hand, I don't know whether Boss Phil would give any "input", actually I mean a "pointer" or a finger to his staff for what direction they should write for each of the DPR reviews, for his own "impressions" on different cameras for particular brands and models, or just his "intentions". But what I can see is that serious inconsistency in judgements and there exists many subjectivities, which overweighs much of the more important facts and thus harms their objectiveness much. When they made their marks and conclusions, I can see many biases, which are rather illogical, with very different "yardsticks" when different cameras are "reviewed" - it can be easily noticeable that they have more tolerances with "large" brands.
Say for example in their K-m review published today, they write in the "Conclusion" that the in-camera jpeg image quality is really rather bad for the K-m and a 6.5 mark out of 10 was given. But in their side-by-side comparison to the Oly E-420, for anyone who can read with a more careful mind, it actually shows there is NOT MUCH difference in the image quality (which they have also mentioned themselves) and that they even say the highlight and shadow transition and preservation are better for the K-m. But then the most ridiculous thing is that they still gave a 8.0 mark for the image quality for the E-420 in their E-420 review.
Whilst I do agree with their preliminary findings that the K-m in-camera jpeg is not on a par with the Canon 1000D (which is true from looking at their posted pictures), and also not as good as the RAW converted jpeg of K-m itself, the quality differences between the K-m against the E-420 and Sony A200 is not of that big differences (with 420's jpegs are close in resolution and A200's slightly better). So, why they did not find serious problems with the Sony and Olympus, even though the Canon is undoubtedly is better, for the evidence they showed.
Hence, they just have very different tailor-made yardsticks for doing different reviews, I must say. IF they compared DSLR to DSLR, all of them should be considered and compared on the same basis, NO MATTER they are Full Frame, APS-C or 4/3. They SHOULD NOT have much more "tolerances" just because the 420 is a 4/3 camera! Silly and stupid enough? (Or maybe the true reason is just about the "brand" behind?)
Whilst they say one of the biggest Cons of the K-m is that "Default JPEGs too contrasty and poorly sharpened" (the first Con they list, which led to the poor marginally "Recommended" rating for the K-m). But then the writers also know well and have mentioned that it is the "default" tone/colour curve as in different regions in the world (actually when the user selects a different language, a different colour/tone profile will be set by the camera). However, since this sharpening level and steep tone curve profile is just a "picture profile" which is just a matter of taste, what "Con" is it actually? How "Big" is that "Con"? What's the fuss about??
2. Incomplete Views by Deemphasizing Shortcomings (of the gear they "like"), Overemphasizing Shortcomings (for gear they "don't like")
Of course, none of we average Internet readers would know the reasons behind for why they actually "like" or "dislike" individual camera of a particular brand and model. But I can see many facts, for example:-
In their very recent Panasonic G1 review (the last review prior to the K-m one), they highly praised the camera and have given the camera very high ratings/overall rating. In fact, I myself have been very interested in the G1 too and I appreciated much the innovativeness and creativity of Panasonic too. Since I have been finding a compact and lightweight DSLR to replace my K100D, I just went to try it. But shortly after I tried it for several minutes, I told myself this camera was not the one I would buy (The set price tag is okay for me). Why? The G1 is a pseudo DSLR with an Electronic ViewFinder (EVF), but that EVF, despite it is quite strong in Spec on paper and is also expensive to make, it is just something not much useful if it is compared to any *optical* viewfinder: Its dynamic range is rather limited - I could not even see those well lit parts of the Pana showroom against those just somehow darker areas at the same time in that environment or vice versa. Pixelisation of the finder image was obvious (owing to the large magnification, which the DPR praise). Flickering of EVF image was obvious. Colour reproduction was fake. So, why STILL the DPR could give the G1 a "Pro" about the EVF of the G1 and praised loudly about its EVF?? If they are mind correct (I mean technically, not commercially) in their methodology, all "DSLRs" under their tests should be considered on the same basis - they should not just because it is the best EVF then they gave it a high mark and even emphasizing it it a "great" "Pro"(!?). The fact is that the EVF of the G1 is *still* far worse than any optical viewfinder, even the worse ones, e.g., those in the 4/3 entry level models - Physics. Owing to the serious biases of the DPR writers, their reviews could be very misleading.
And, as for the K-m review, another major reason they told the world for giving such a rarely seen and low rating (by now and in recent years) and why they are so disliked about the camera is yet unsubstantiated (putting aside the inferior in-camera jpeg (but yet they do not mention about the best retained colours and details by the K-m at higher ISO speeds), which is: The missing selected AF point indication (the illuminated red-points).
It should be noted that the K-m has only five AF points which are put very closely to the frame centre (which is still more than a few of those "Highly Recommended" current entry level DSLRs by other brands). In the following, I would talk more about that red indication from the viewpoint of a Photographer and then more from an Engineer.
First, from the user point of view, practically:-
A. For stationary objects: If the user want to have total control on the selection of focus point (and for knowing where the focus will fall on), he/she just has chosen the (Single) Central AF point already and do re-composition for each frame when taking the pictures. On the other hand, if the user, whom is usually a beginner or novice, let the camera decide and choose the AF point *automatically* for him/her, WHY the user cares about which point? Why it is needed? Will they care? Of course, if there is such an indication, it is mostly welcomed. But I don't think it is a serious flaw, never; and
B. For moving objects: Actually, under most circumstances, it is more important to know which focus point(s) the camera has chosen, since practically it is not feasible to re-compose and time usually does not allow. Indeed, I want the indication for my Canon 5D too. I did write at the DPR long time ago when I first got my 5D for asking Canon to implement it, at least as an option. But waaait, do Uncle and Boss Phil knows *even* the Canon 1 series truly professional DSLRs, namely, IDS and 1D MkIII, will have the red AF illuminations disabled in the Continuous / Servo AF mode (Yes, I am sure that they know!). So, what's the point, then?? And, why didn't DPR give the Canon flagships low marks and then "not recommending" the EOS 1D and IDS bodies because of this reason??? In fact, they have never done that, and never dared not and will never dare to do so (and of course!). All Nikon DSLRs have the indication even in Servo AF mode (as I have said, at least as an option - IIRC), so why not DPR trashed the Canons?
Now, from the technical point of view, the entry level Canons, say, the 1000D AF point indication is just a small and weakly illuminated red point which is hardly visible, especially when shooting outdoor, which just means that it is not much better. Since the 1000D has a particularly small viewfinder vision, such indication is yet not as useful as it would be, theoretically. In contrast, the K-m does have the largest viewfinder image magnification amongst all entry level DSLRs, which is undoubtedly larger than that of the 1000D and D60, so why didn't Uncle Phil's guys emphasize this so strongly?? (There is only one brief and vague statement mentioned in the whole review)
All in all, should the above two most "important" and "killing" shortcomings really worth for so many marks to be deducted. With such weak reasons and "grounds" to finally draw up a "Recommended (with Reservation)" rating, I am totally not convinced. It just looks like some simple excuses were to be found and it's time for DPR to show their "objectiveness", since they have just given too many and so many "Highly Recommended" ratings in recent years. And, as you can see the numerous responses on the Net already, conspiracy theory will come in again for the true reasons behind..
On the other hand, I wish to point out that the K-m does not have the LiveView function (technically fully explained here), why the DPR don't even mention this as a "Con", which is a more valid point IMO. Would it be just because the *Nikon* D60 also doesn't have that? In their D60 review, this is even not listed as one of the Cons, neither. Really very good "consistency! Well done, DPR! They were most brilliant and clear enough to mention that discrepancy in the words of the Conclusion, which are well hidden, together with some kinds of defense. In fact, for what I know about those new DSLR beginners, especially whom used to shoot with P&S or Prosumer DCs but no DSLR reflex experience before, LiveView is just a feature on the top of their requirement lists when they are to make their choice (whether the LiveView will be useful to them or not when they have their DSLRs is yet another problem).
P.S. I have all those entry level Canon and Nikon DSLRs at work and I myself own and use so many Pentax DSLRs and also a high-end Canon Full Frame DSLR. As such, I believe I actually know very well for all those practical differences, between different models by different makers.
3. Unqualified Incompetent Persons; Not Observing International/Industrial Standards; Infringement to the Intellectual Property of the ISO
- DPR measure resolution values by human eyes, with no consideration of the MTF % or simply ignore it completely! Note: MTF - Modulation Transfer Function, fully explained here (by Norman Koren), here (by Bob Atkins), here (by Michael Reichmann) and here (by Ken Rockwell). Well, DPR don't know about MTF??
- DPR do not test exposure accuracy based on Standards, not even they recorded and shown any histogram before they commented on the "exposure accuracy" of the DSLRs (Funny). But then you can download all their stuff, inspect the EXIF data, view the histograms and compare, if you have the time!
- DPR do not test AF timings before they made so many "Conclusions". Oh, yes, they concluded by *Opinions* and *Impression*, I almost forget.
- DPR do not test AF accuracy! No object/chart was tested/posted but they dared to comment! So, what's the difference of those "technical writers" from an Average Joe who writes at any user commenting websites like the Epinions. All these, including those made by the DPR, are just individual *user comments* afterall, which are based on nothing!
- DPR do not test system time lags of the DSLRs, which is just a key manufacturer's performance spec which is usually not published, as opposed to what Japanese CIPA and Imaging Resource measures.
- DPR (and actually Phil) even dared to steal and modify the ISO test chart (which Phil bought long ago) for measuring resolution and then marked a "copyrighted" by the DPR!? He is just so much conceited but was not even aware that it is illegal! Didn't Uncle Phil know that the ISO test chart was and is still copyrighted by the ISO and is the Intellectual Property owned by the ISO, not the DPR! (and of course not by Phil Askey personally - he was just one of the customers of the ISO publications!)
- DPR technical writers and editor (i.e., Phil Askey) have no professional qualification of any kind shown and told by them as related to the industry and field. Phil only told us that he was an IT man.
- And so on.. (but I would stop here, you *think* and *judge* yourself!)
Well, besides all the above facts and "Cons" of the DPR (Now I have almost completely "reviewed" them! Haha), there are more to note for the global Internet atmosphere and trend:-
1. Decreasing Reference Values
Last but not least, with the rise of Web 2.0 and interactive information and data sharing platforms, there are more and more useful materials shared on the Net daily such as Blogs (from different persons) and those end-users posted sample photos, which could be very valuable if the readers can select carefully and most importantly, those information could be more *honest* and "faithful". Other than the DPR, we now have much many choices at places like Blogger, Flickr, YouTube, or even Facebook and more. If you like, you can still pixel peeping on those un-retouched original images (till the end of the world!) which are not intentionally selected and picked. So, what are the true values of those primly commercial websites run by *merchants* with incompetent employees nowadays??
2. Conflicts of Interests
I think quite many people have already forgotten that DPR and so many alike sites are just running solely commercially, despite that they seem to be providing "free" (really?) services to the *end-users*? But what are their sources of incomes?? How come they could and can earn a living? And, when and under what situations they will be unable to survive and need to close down?? (And then they need to find a job after losing their *businesses*! ;-) Are they afraid?)
Go find the simple answers yourself!
Conclusion and My Humble Final Reminders
DO NOT take personal opinions solely and heavily relied just on *one* single source, no matter how authoritive the source looks or you think to be. Do more researches by reading more other articles and read more honest user opinions as well. Only by doing that, you can gather more facts, INSTEAD of subjective opinions and comments (including those by so-called self-claimed "technical writers" or "reviewers" who earn money for a living from all those associated commercial deals and Ads.
But on the other hand, do totally BEWARE of those brand-blinded fanboys and their opinions, which must be filtered out! When you see persons who always do not allow anyone to say anything "negative" on *any* shortcomings of "their" gear (they particularly are very sensitive to the "brand" they ""own"") and/or just that "their" gear are *always* "perfect, you should IGNORE THEM totally! And of course, whilst I believe that I am totally honest enough, please also don't take my words solely neither, do read my this disclaimer for why, just in case if you have not yet!
Most importantly, do try out your interested camera gear *yourself* hands-on before you act. Otherwise, you will have remorse!
With this trend of declining quality reviews for what DPR give us, I bet that the site will be going on a down slope in the long future once the internet community recognises that it is no more a reliable and valuable resource. Actually some more better sites which are carrying gear tests in a professional manner are coming up recently, like the DxOMark.com (and my report of its birth here), with a very good web interface too. So if you really intend to measur(e)bate and pixel-peep, do read better sites instead of those sub-standard ones! For old sites, I would rather recommend the "friend" site of DPR, the Imaging Resource, at least their camera reviews are based on the Imatest for some of their tests, which is using the ISO standards, e.g., for the exposure and colour accuracy tests, and they did select more sensible camera performance parameters to measure than the DPR.
The Earth is rotating, years ago, the type of DPR reviews and standard report format might be still good enough to satisfy the needs of the Internet audience and readers, owing to the limited information and little competition on the Net, as I have said in the beginning. Nowadays, in 2009, with the more advanced Web 2.0 and open platforms for all Internet users, I think the one-way information sharing is just outdated. In fact, I have seen no real improvement of the DPR website (their web design is dated - when you use different machines to view their pages and you will know what I am talking about) and more importantly their tests and the way they made their tests are dated also.
Lastly, I would remind here anyone to think twice and twice again if he/she is still really to make purchasing decision solely based on the DPR "reviews". My final humble advice: Take the DPR reviews nowadays as grains of salt. If you read, read their RAW materials presented *first*, which are readily downloadable from their site. Judge the materials they put but not the words from their mouths, never. They just give misleading and partial conclusions, owing to many many reasons.
But then about ten years ago, there came the DPReview (DPR) website, which the site owner Phil Askey used to call his user reports on digital cameras and gear as "reviews". Those reports of him were just summaries of his personal findings (based on some very simple "measurements" or even not), comments and opinions about the gear: no more, no less. Since at that time, there was not much useful information on the Internet and ditto for many of those printed magazines, in which most of the "test" reports are almost useless, the DPR became more and more popular and "large". A good example for those limited information age of the Internet is no better to quote the Steve's Digicams which produced really crappy useless "reviews" (you'd better download an official user manual from an official site and could get more info about the cameras!) could still earn a living! Nowadays, the term "review" has now been widely accepted and has a generalised meaning for any gear test or comment report, regardless of how they were done, i.e., anyone can write a "review", from a novice who knows almost nothing versus a real expert who has been working in the industry for years and has acquired different professional qualifications in the relevant fields and areas of the industry.
So, let me go back to the topic. What makes me to write this blog article immediately is that I can see the quality, usefulness and creditability of those published camera reviews by the DPR are declining. But yet I know that the general public of the Internet *still* trust too much the DPR (well, it is just a tradition by now). The general audience, whom are huge for those who read their site, just rely too heavily on their reports. For all these reasons, I opt to write here something to share my observations and thoughts with a sole intention to draw the attention of any of those internet readers for the flaws and problems of those DPR reviews (more so recently, and also the upcoming reviews, very likely). In fact, I can see that DPR and Phil Askey have spent no more new effort in improving the quality and standard of their reviews with better contents. Instead, Phil's crew and staff who called themselves as "technical writers", are just knowing to follow strictly the old report template that has been used by their boss for long, which IMO is just rather outdated by today's standards.
Now, let's go on to see why the DPR reviews are now so problematic. I will elaborate more in details with *some* examples:-
1. Inconsistent Judgements/Yardsticks
Since Uncle Phil sold his DPR site to Amazon and became the Overlord of the site, he employed a team of crew of his own so that Phil could have more time to enjoy more of his life from his hard earned money, which should not be a small sum as Amazon is just a very large company! Well, just think if you had the money, you would want more time, so that you could spend your money! Right? :-)
But after that, all the DPR reviews were written by different person(s), sometimes one, sometimes two, sometimes three and sometimes four. Phil sometimes participated with his name appeared as one of the reviewers, but not often. But then what's the (real) problem? With different combinations of different persons as the reviewers, their viewpoints, judgements or simply prejudgements could be very different, even though it seems that there is a well-established "system, which is just more or less a document template for the review report format.
Nevertheless, on the other hand, I don't know whether Boss Phil would give any "input", actually I mean a "pointer" or a finger to his staff for what direction they should write for each of the DPR reviews, for his own "impressions" on different cameras for particular brands and models, or just his "intentions". But what I can see is that serious inconsistency in judgements and there exists many subjectivities, which overweighs much of the more important facts and thus harms their objectiveness much. When they made their marks and conclusions, I can see many biases, which are rather illogical, with very different "yardsticks" when different cameras are "reviewed" - it can be easily noticeable that they have more tolerances with "large" brands.
Say for example in their K-m review published today, they write in the "Conclusion" that the in-camera jpeg image quality is really rather bad for the K-m and a 6.5 mark out of 10 was given. But in their side-by-side comparison to the Oly E-420, for anyone who can read with a more careful mind, it actually shows there is NOT MUCH difference in the image quality (which they have also mentioned themselves) and that they even say the highlight and shadow transition and preservation are better for the K-m. But then the most ridiculous thing is that they still gave a 8.0 mark for the image quality for the E-420 in their E-420 review.
Whilst I do agree with their preliminary findings that the K-m in-camera jpeg is not on a par with the Canon 1000D (which is true from looking at their posted pictures), and also not as good as the RAW converted jpeg of K-m itself, the quality differences between the K-m against the E-420 and Sony A200 is not of that big differences (with 420's jpegs are close in resolution and A200's slightly better). So, why they did not find serious problems with the Sony and Olympus, even though the Canon is undoubtedly is better, for the evidence they showed.
Hence, they just have very different tailor-made yardsticks for doing different reviews, I must say. IF they compared DSLR to DSLR, all of them should be considered and compared on the same basis, NO MATTER they are Full Frame, APS-C or 4/3. They SHOULD NOT have much more "tolerances" just because the 420 is a 4/3 camera! Silly and stupid enough? (Or maybe the true reason is just about the "brand" behind?)
Whilst they say one of the biggest Cons of the K-m is that "Default JPEGs too contrasty and poorly sharpened" (the first Con they list, which led to the poor marginally "Recommended" rating for the K-m). But then the writers also know well and have mentioned that it is the "default" tone/colour curve as in different regions in the world (actually when the user selects a different language, a different colour/tone profile will be set by the camera). However, since this sharpening level and steep tone curve profile is just a "picture profile" which is just a matter of taste, what "Con" is it actually? How "Big" is that "Con"? What's the fuss about??
2. Incomplete Views by Deemphasizing Shortcomings (of the gear they "like"), Overemphasizing Shortcomings (for gear they "don't like")
Of course, none of we average Internet readers would know the reasons behind for why they actually "like" or "dislike" individual camera of a particular brand and model. But I can see many facts, for example:-
In their very recent Panasonic G1 review (the last review prior to the K-m one), they highly praised the camera and have given the camera very high ratings/overall rating. In fact, I myself have been very interested in the G1 too and I appreciated much the innovativeness and creativity of Panasonic too. Since I have been finding a compact and lightweight DSLR to replace my K100D, I just went to try it. But shortly after I tried it for several minutes, I told myself this camera was not the one I would buy (The set price tag is okay for me). Why? The G1 is a pseudo DSLR with an Electronic ViewFinder (EVF), but that EVF, despite it is quite strong in Spec on paper and is also expensive to make, it is just something not much useful if it is compared to any *optical* viewfinder: Its dynamic range is rather limited - I could not even see those well lit parts of the Pana showroom against those just somehow darker areas at the same time in that environment or vice versa. Pixelisation of the finder image was obvious (owing to the large magnification, which the DPR praise). Flickering of EVF image was obvious. Colour reproduction was fake. So, why STILL the DPR could give the G1 a "Pro" about the EVF of the G1 and praised loudly about its EVF?? If they are mind correct (I mean technically, not commercially) in their methodology, all "DSLRs" under their tests should be considered on the same basis - they should not just because it is the best EVF then they gave it a high mark and even emphasizing it it a "great" "Pro"(!?). The fact is that the EVF of the G1 is *still* far worse than any optical viewfinder, even the worse ones, e.g., those in the 4/3 entry level models - Physics. Owing to the serious biases of the DPR writers, their reviews could be very misleading.
And, as for the K-m review, another major reason they told the world for giving such a rarely seen and low rating (by now and in recent years) and why they are so disliked about the camera is yet unsubstantiated (putting aside the inferior in-camera jpeg (but yet they do not mention about the best retained colours and details by the K-m at higher ISO speeds), which is: The missing selected AF point indication (the illuminated red-points).
It should be noted that the K-m has only five AF points which are put very closely to the frame centre (which is still more than a few of those "Highly Recommended" current entry level DSLRs by other brands). In the following, I would talk more about that red indication from the viewpoint of a Photographer and then more from an Engineer.
First, from the user point of view, practically:-
A. For stationary objects: If the user want to have total control on the selection of focus point (and for knowing where the focus will fall on), he/she just has chosen the (Single) Central AF point already and do re-composition for each frame when taking the pictures. On the other hand, if the user, whom is usually a beginner or novice, let the camera decide and choose the AF point *automatically* for him/her, WHY the user cares about which point? Why it is needed? Will they care? Of course, if there is such an indication, it is mostly welcomed. But I don't think it is a serious flaw, never; and
B. For moving objects: Actually, under most circumstances, it is more important to know which focus point(s) the camera has chosen, since practically it is not feasible to re-compose and time usually does not allow. Indeed, I want the indication for my Canon 5D too. I did write at the DPR long time ago when I first got my 5D for asking Canon to implement it, at least as an option. But waaait, do Uncle and Boss Phil knows *even* the Canon 1 series truly professional DSLRs, namely, IDS and 1D MkIII, will have the red AF illuminations disabled in the Continuous / Servo AF mode (Yes, I am sure that they know!). So, what's the point, then?? And, why didn't DPR give the Canon flagships low marks and then "not recommending" the EOS 1D and IDS bodies because of this reason??? In fact, they have never done that, and never dared not and will never dare to do so (and of course!). All Nikon DSLRs have the indication even in Servo AF mode (as I have said, at least as an option - IIRC), so why not DPR trashed the Canons?
Now, from the technical point of view, the entry level Canons, say, the 1000D AF point indication is just a small and weakly illuminated red point which is hardly visible, especially when shooting outdoor, which just means that it is not much better. Since the 1000D has a particularly small viewfinder vision, such indication is yet not as useful as it would be, theoretically. In contrast, the K-m does have the largest viewfinder image magnification amongst all entry level DSLRs, which is undoubtedly larger than that of the 1000D and D60, so why didn't Uncle Phil's guys emphasize this so strongly?? (There is only one brief and vague statement mentioned in the whole review)
All in all, should the above two most "important" and "killing" shortcomings really worth for so many marks to be deducted. With such weak reasons and "grounds" to finally draw up a "Recommended (with Reservation)" rating, I am totally not convinced. It just looks like some simple excuses were to be found and it's time for DPR to show their "objectiveness", since they have just given too many and so many "Highly Recommended" ratings in recent years. And, as you can see the numerous responses on the Net already, conspiracy theory will come in again for the true reasons behind..
On the other hand, I wish to point out that the K-m does not have the LiveView function (technically fully explained here), why the DPR don't even mention this as a "Con", which is a more valid point IMO. Would it be just because the *Nikon* D60 also doesn't have that? In their D60 review, this is even not listed as one of the Cons, neither. Really very good "consistency! Well done, DPR! They were most brilliant and clear enough to mention that discrepancy in the words of the Conclusion, which are well hidden, together with some kinds of defense. In fact, for what I know about those new DSLR beginners, especially whom used to shoot with P&S or Prosumer DCs but no DSLR reflex experience before, LiveView is just a feature on the top of their requirement lists when they are to make their choice (whether the LiveView will be useful to them or not when they have their DSLRs is yet another problem).
P.S. I have all those entry level Canon and Nikon DSLRs at work and I myself own and use so many Pentax DSLRs and also a high-end Canon Full Frame DSLR. As such, I believe I actually know very well for all those practical differences, between different models by different makers.
3. Unqualified Incompetent Persons; Not Observing International/Industrial Standards; Infringement to the Intellectual Property of the ISO
- DPR measure resolution values by human eyes, with no consideration of the MTF % or simply ignore it completely! Note: MTF - Modulation Transfer Function, fully explained here (by Norman Koren), here (by Bob Atkins), here (by Michael Reichmann) and here (by Ken Rockwell). Well, DPR don't know about MTF??
- DPR do not test exposure accuracy based on Standards, not even they recorded and shown any histogram before they commented on the "exposure accuracy" of the DSLRs (Funny). But then you can download all their stuff, inspect the EXIF data, view the histograms and compare, if you have the time!
- DPR do not test AF timings before they made so many "Conclusions". Oh, yes, they concluded by *Opinions* and *Impression*, I almost forget.
- DPR do not test AF accuracy! No object/chart was tested/posted but they dared to comment! So, what's the difference of those "technical writers" from an Average Joe who writes at any user commenting websites like the Epinions. All these, including those made by the DPR, are just individual *user comments* afterall, which are based on nothing!
- DPR do not test system time lags of the DSLRs, which is just a key manufacturer's performance spec which is usually not published, as opposed to what Japanese CIPA and Imaging Resource measures.
- DPR (and actually Phil) even dared to steal and modify the ISO test chart (which Phil bought long ago) for measuring resolution and then marked a "copyrighted" by the DPR!? He is just so much conceited but was not even aware that it is illegal! Didn't Uncle Phil know that the ISO test chart was and is still copyrighted by the ISO and is the Intellectual Property owned by the ISO, not the DPR! (and of course not by Phil Askey personally - he was just one of the customers of the ISO publications!)
- DPR technical writers and editor (i.e., Phil Askey) have no professional qualification of any kind shown and told by them as related to the industry and field. Phil only told us that he was an IT man.
- And so on.. (but I would stop here, you *think* and *judge* yourself!)
Well, besides all the above facts and "Cons" of the DPR (Now I have almost completely "reviewed" them! Haha), there are more to note for the global Internet atmosphere and trend:-
1. Decreasing Reference Values
Last but not least, with the rise of Web 2.0 and interactive information and data sharing platforms, there are more and more useful materials shared on the Net daily such as Blogs (from different persons) and those end-users posted sample photos, which could be very valuable if the readers can select carefully and most importantly, those information could be more *honest* and "faithful". Other than the DPR, we now have much many choices at places like Blogger, Flickr, YouTube, or even Facebook and more. If you like, you can still pixel peeping on those un-retouched original images (till the end of the world!) which are not intentionally selected and picked. So, what are the true values of those primly commercial websites run by *merchants* with incompetent employees nowadays??
2. Conflicts of Interests
I think quite many people have already forgotten that DPR and so many alike sites are just running solely commercially, despite that they seem to be providing "free" (really?) services to the *end-users*? But what are their sources of incomes?? How come they could and can earn a living? And, when and under what situations they will be unable to survive and need to close down?? (And then they need to find a job after losing their *businesses*! ;-) Are they afraid?)
Go find the simple answers yourself!
Conclusion and My Humble Final Reminders
DO NOT take personal opinions solely and heavily relied just on *one* single source, no matter how authoritive the source looks or you think to be. Do more researches by reading more other articles and read more honest user opinions as well. Only by doing that, you can gather more facts, INSTEAD of subjective opinions and comments (including those by so-called self-claimed "technical writers" or "reviewers" who earn money for a living from all those associated commercial deals and Ads.
But on the other hand, do totally BEWARE of those brand-blinded fanboys and their opinions, which must be filtered out! When you see persons who always do not allow anyone to say anything "negative" on *any* shortcomings of "their" gear (they particularly are very sensitive to the "brand" they ""own"") and/or just that "their" gear are *always* "perfect, you should IGNORE THEM totally! And of course, whilst I believe that I am totally honest enough, please also don't take my words solely neither, do read my this disclaimer for why, just in case if you have not yet!
Most importantly, do try out your interested camera gear *yourself* hands-on before you act. Otherwise, you will have remorse!
With this trend of declining quality reviews for what DPR give us, I bet that the site will be going on a down slope in the long future once the internet community recognises that it is no more a reliable and valuable resource. Actually some more better sites which are carrying gear tests in a professional manner are coming up recently, like the DxOMark.com (and my report of its birth here), with a very good web interface too. So if you really intend to measur(e)bate and pixel-peep, do read better sites instead of those sub-standard ones! For old sites, I would rather recommend the "friend" site of DPR, the Imaging Resource, at least their camera reviews are based on the Imatest for some of their tests, which is using the ISO standards, e.g., for the exposure and colour accuracy tests, and they did select more sensible camera performance parameters to measure than the DPR.
The Earth is rotating, years ago, the type of DPR reviews and standard report format might be still good enough to satisfy the needs of the Internet audience and readers, owing to the limited information and little competition on the Net, as I have said in the beginning. Nowadays, in 2009, with the more advanced Web 2.0 and open platforms for all Internet users, I think the one-way information sharing is just outdated. In fact, I have seen no real improvement of the DPR website (their web design is dated - when you use different machines to view their pages and you will know what I am talking about) and more importantly their tests and the way they made their tests are dated also.
Lastly, I would remind here anyone to think twice and twice again if he/she is still really to make purchasing decision solely based on the DPR "reviews". My final humble advice: Take the DPR reviews nowadays as grains of salt. If you read, read their RAW materials presented *first*, which are readily downloadable from their site. Judge the materials they put but not the words from their mouths, never. They just give misleading and partial conclusions, owing to many many reasons.
Friday, January 30, 2009
Strange K20D Noise Patterns
Various K20D users at the PentaxForums have reported that they experienced strange pattern noises which appear in particular regions of a frame and are particularly noticeable at ISO speeds higher than ISO 1600:-
http://www.pentaxforums.com/forums/pentax-dslr-discussion/47584-strange-k20d-high-iso-noise-patterns.html
All the user reports in the above thread are self-explanatory, with sample pictures posted and the issues found are clearly described.
But yet a particular user who has a very careful mind found that "the K20D has a strange vertical bar at the left side of the image, visible (normally) only by extreme pushing the contrast and brightness" here, in his this reply post.
He further states that, "So far I was able to produce it with every K20D I saw."
Actually, this "vertical bar" can also be seen at ISO 100 at which the situation is the "best", see another follow-up post from the same poster. A histogram for shooting a dark frame is posted.
The strangest thing here is that the unevenly distributed pattern noises are appearing in particular regions, and particularly existent in the Blue channel. They appear at image corners, left side or at the top and bottom of the frame. They appear not only at high ISO speeds but also at lowest ISO 100. It is only that the noises are much more obvious at high ISO speeds whereas at low speeds, they are well hidden but push processing or any kinds of more "extreme" post processing will reveal all these.
So, the culprit? It should be an immature sensor and associated hardware (and may also be the associated software) used in the K20D, which are to be debugged!
Indeed, I hope Samsung will do their debug jobs quicker and faster so that it makes it possible for Pentax to roll out their K20D replacement model soonest (as it should be). If not, Pentax should really source and get another sensor unit to put it into the K20D replacement, IMHO. In fact, the K20D is essentially a dead model now, for what the limited number of sales and low popularity/availability as seen. There are less and less shops carry the K20D and it can be hardly found. And even for rare places where the K20D can be found, they are just sitting there for collecting dust despite the K20D are now selling for very little money (very close to the 450D kit price).
Read Also:-
K20D has VPN under Cold Temperature?
K20D Banding Problem Reported at Low ISO Speed
http://www.pentaxforums.com/forums/pentax-dslr-discussion/47584-strange-k20d-high-iso-noise-patterns.html
All the user reports in the above thread are self-explanatory, with sample pictures posted and the issues found are clearly described.
But yet a particular user who has a very careful mind found that "the K20D has a strange vertical bar at the left side of the image, visible (normally) only by extreme pushing the contrast and brightness" here, in his this reply post.
He further states that, "So far I was able to produce it with every K20D I saw."
Actually, this "vertical bar" can also be seen at ISO 100 at which the situation is the "best", see another follow-up post from the same poster. A histogram for shooting a dark frame is posted.
The strangest thing here is that the unevenly distributed pattern noises are appearing in particular regions, and particularly existent in the Blue channel. They appear at image corners, left side or at the top and bottom of the frame. They appear not only at high ISO speeds but also at lowest ISO 100. It is only that the noises are much more obvious at high ISO speeds whereas at low speeds, they are well hidden but push processing or any kinds of more "extreme" post processing will reveal all these.
So, the culprit? It should be an immature sensor and associated hardware (and may also be the associated software) used in the K20D, which are to be debugged!
Indeed, I hope Samsung will do their debug jobs quicker and faster so that it makes it possible for Pentax to roll out their K20D replacement model soonest (as it should be). If not, Pentax should really source and get another sensor unit to put it into the K20D replacement, IMHO. In fact, the K20D is essentially a dead model now, for what the limited number of sales and low popularity/availability as seen. There are less and less shops carry the K20D and it can be hardly found. And even for rare places where the K20D can be found, they are just sitting there for collecting dust despite the K20D are now selling for very little money (very close to the 450D kit price).
Read Also:-
K20D has VPN under Cold Temperature?
K20D Banding Problem Reported at Low ISO Speed
Wednesday, January 28, 2009
My Second Tests on the K-m and Observations
Further to my first trial on the K-m previously, I tried the K-m recently for three more times, with a DAL 18-55 kit, my (crippled) 43 Limited and FA 24-90 on the body respectively, separately for 3 different K-m demo units at different places. Here are something interesting or special to share:-
1. AF is overall fast and smooth. Even for my FA 43, which has been renowned as one of the most slow (and noisy) focusing lens for its AF (mechanism). Hunting was non-existent and minimal when it came near the final focus point, especially when the lens was at f/2.8 or wider. Since that 43 Limited lens has a particularly long run for its AF range, and it's also noisy, I could feel well and note more clearly about the speed control of the whole AF process, by the K-m's "new" AF system. I found that the control was more precise and speed changes were smoother - the best I have seen for a Pentax DSLR ever! Now, the K-m feels more like my Canon (5D), although the AF motor speed is slower, as long as a fast AF lens is used.
2. Exposures were found to be very accurate under white light environment, whilst under yellow light, it still underexposed a bit, unfortunately.
3. Since both of my above Pentax lenses used had the aperture coupler removed, I could easily checked about the exposure accuracy and consistency of the K-m's stop-down metering. I tried with my 43 Limited with apertures set from f/2.8 to f/11 at each f-stop. To my really BIG surprise, the results were *dead* accurate, for the first time for a Pentax DSLR (which I have used all, for all major models!). My experiences were that my *ist D/DS and K100D used to underexpose more (and much) when stopped down (more) and the K10D/K20D did overexpose (more and much) when stopped down (further). So, this must the greatest improvement I have ever seen for a Pentax DSLR as long as exposure accuracy is concerned!
4. Viewfinder is yet bright and easy to see until f/5.6. But since its magnification is not high, the DoF could not be easily seen, though. Anyway, it would be fairer to mention that the finder's view is yet noticeable larger than that of the D60 and the EOS 1000D and of course far better than the super tunnel view of the 4/3 E-520.
5. Build quality is very good and I found it to be the best if it has to be compared against other entry level DSLRs like the D60, 1000D, E-520 etc. I found the K-m felt more solid than my K100D which I have owned for long. The RTF (built-in flash) can be closed very tightly without any play for one of the demo units (whereas the other two are okay). So, if you have the luck, you can get a perfect one.
6. Size is the smallest amongst the above competing entry level models mentioned (and actually I compared them size by size for all of them). The K-m is even smaller than the 4/3 E-520, although not lighter. The DAL 18-55 kit lens is smaller (and lighter?) than the Canon and Nikon ones. The Oly standard kit is smallest and lightest but the Pentax's is an APS-C lens anyway instead of the smaller 4/3 format anyway.
7. Weight is *acceptable* with NiMH AA rechargeables. With AA Lithums, it feels less heavy.
8. Last but not least, I found that overall the K-m's ergonomics are good to excellent. The body's grip is very good to hold despite the small size of the K-m, better than my "small size" Pentax DSLRs like the *ist DS, D and K100D. The overall balance of the body felt very well as the heavy AA rechargeables in the grip yet contributes to stability at the right ;-). And, contrary to some K-m users reported, I found no problem in operating the column of standard four DSLR buttons which are now re-located at the right side, and can now be operated easily by the thumb, which I found it to be even a good thing just in one hand, with the right hand only. :-)
9. Finally, FIMW mentioning, the external colour LCD display, which is the only LCD display in the camera now (since there is now no top monochrome status LCD panel), will be turned on when the shutter release button is *first* half-pressed. When the shutter release button is half-pressed again, the external LCD will be turned off. If the user has already looked through the viewfinder, it will do the AF and AE as usual and turn off the external LCD at the same time as it may be a nuisance when the eye is looking at the finder, especially in dark environment. In fact, I carried out the above operations smoothly and naturally without any problem and I think Pentax's engineers have done a good job with a thoughtful design.
Overall, I am quite pleased with the K-m after my second series of trials with it. I particularly feel excited for the improved exposure accuracies, particularly for the 1st time reliability for stop-down metering which has not been seen for a Pentax DSLR before! (needed to be verified more fully - I cannot guarantee here 100% unless I have owned the camera!).
All in all, I would say the K-m is a very good DSLR, which I can see Pentax should have paid a lot of efforts in debugging their line of (somehow problematic, frankly) DSLRs, despite that they have made it very late, I think still "Late is better than None"! Still, I would give Pentax a "Well Done!" comment here, at my Blog! (which is not easy and should be very "valuable"! ;-D)
As my last remarks, for anyone who is considering the K-m (including me of course :-)), I would still like to remind that there are still two (might be important things, depending on usage) are omitted and missing in the K-m, namely: 1. There is no cable switch socket; 2. There is not an SR on/off switch/lever - The SR on/off is now to be selected via the camera's menu. And, as usual, the SR is recommended to be turned off when the camera is mounted on a tripod or when the user is doing pan shots.
1. AF is overall fast and smooth. Even for my FA 43, which has been renowned as one of the most slow (and noisy) focusing lens for its AF (mechanism). Hunting was non-existent and minimal when it came near the final focus point, especially when the lens was at f/2.8 or wider. Since that 43 Limited lens has a particularly long run for its AF range, and it's also noisy, I could feel well and note more clearly about the speed control of the whole AF process, by the K-m's "new" AF system. I found that the control was more precise and speed changes were smoother - the best I have seen for a Pentax DSLR ever! Now, the K-m feels more like my Canon (5D), although the AF motor speed is slower, as long as a fast AF lens is used.
2. Exposures were found to be very accurate under white light environment, whilst under yellow light, it still underexposed a bit, unfortunately.
3. Since both of my above Pentax lenses used had the aperture coupler removed, I could easily checked about the exposure accuracy and consistency of the K-m's stop-down metering. I tried with my 43 Limited with apertures set from f/2.8 to f/11 at each f-stop. To my really BIG surprise, the results were *dead* accurate, for the first time for a Pentax DSLR (which I have used all, for all major models!). My experiences were that my *ist D/DS and K100D used to underexpose more (and much) when stopped down (more) and the K10D/K20D did overexpose (more and much) when stopped down (further). So, this must the greatest improvement I have ever seen for a Pentax DSLR as long as exposure accuracy is concerned!
4. Viewfinder is yet bright and easy to see until f/5.6. But since its magnification is not high, the DoF could not be easily seen, though. Anyway, it would be fairer to mention that the finder's view is yet noticeable larger than that of the D60 and the EOS 1000D and of course far better than the super tunnel view of the 4/3 E-520.
5. Build quality is very good and I found it to be the best if it has to be compared against other entry level DSLRs like the D60, 1000D, E-520 etc. I found the K-m felt more solid than my K100D which I have owned for long. The RTF (built-in flash) can be closed very tightly without any play for one of the demo units (whereas the other two are okay). So, if you have the luck, you can get a perfect one.
6. Size is the smallest amongst the above competing entry level models mentioned (and actually I compared them size by size for all of them). The K-m is even smaller than the 4/3 E-520, although not lighter. The DAL 18-55 kit lens is smaller (and lighter?) than the Canon and Nikon ones. The Oly standard kit is smallest and lightest but the Pentax's is an APS-C lens anyway instead of the smaller 4/3 format anyway.
7. Weight is *acceptable* with NiMH AA rechargeables. With AA Lithums, it feels less heavy.
8. Last but not least, I found that overall the K-m's ergonomics are good to excellent. The body's grip is very good to hold despite the small size of the K-m, better than my "small size" Pentax DSLRs like the *ist DS, D and K100D. The overall balance of the body felt very well as the heavy AA rechargeables in the grip yet contributes to stability at the right ;-). And, contrary to some K-m users reported, I found no problem in operating the column of standard four DSLR buttons which are now re-located at the right side, and can now be operated easily by the thumb, which I found it to be even a good thing just in one hand, with the right hand only. :-)
9. Finally, FIMW mentioning, the external colour LCD display, which is the only LCD display in the camera now (since there is now no top monochrome status LCD panel), will be turned on when the shutter release button is *first* half-pressed. When the shutter release button is half-pressed again, the external LCD will be turned off. If the user has already looked through the viewfinder, it will do the AF and AE as usual and turn off the external LCD at the same time as it may be a nuisance when the eye is looking at the finder, especially in dark environment. In fact, I carried out the above operations smoothly and naturally without any problem and I think Pentax's engineers have done a good job with a thoughtful design.
Overall, I am quite pleased with the K-m after my second series of trials with it. I particularly feel excited for the improved exposure accuracies, particularly for the 1st time reliability for stop-down metering which has not been seen for a Pentax DSLR before! (needed to be verified more fully - I cannot guarantee here 100% unless I have owned the camera!).
All in all, I would say the K-m is a very good DSLR, which I can see Pentax should have paid a lot of efforts in debugging their line of (somehow problematic, frankly) DSLRs, despite that they have made it very late, I think still "Late is better than None"! Still, I would give Pentax a "Well Done!" comment here, at my Blog! (which is not easy and should be very "valuable"! ;-D)
As my last remarks, for anyone who is considering the K-m (including me of course :-)), I would still like to remind that there are still two (might be important things, depending on usage) are omitted and missing in the K-m, namely: 1. There is no cable switch socket; 2. There is not an SR on/off switch/lever - The SR on/off is now to be selected via the camera's menu. And, as usual, the SR is recommended to be turned off when the camera is mounted on a tripod or when the user is doing pan shots.
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