Saturday, February 28, 2009

Pentax Service Manuals

http://www.pentax-manuals.com/manuals/service/servicemanuals.htm

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!

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.

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?

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!)

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.

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!)

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