Friday, March 30, 2007

K100D SD Card Write Speed Test

Here is a simple SD card write speed test with my K100D, for some SD cards of different brands and models, each of which has different rated read and write speeds, if any specified:-

Card and IdentifierRated SpeedChipset
Write Time for 3 PEFs
(Rounded Up to
the Nearest Second)
Throughput
EagleTec 256MB SD
"SAMSUNG 334
K9K2G08U0M-YCB0
ULG023PX"
Nil
Samsung
17 s
1.79 MB/s
Lexar 1GB SD
"LEXAR MEDIA SD1GB-120M
1405112
A040507B
MADE IN U.S.A."
Nil
Lexar
12 s
2.54 MB/s
Toshiba 1GB SD
"Toshiba SD-M01G
0508TJ8419L
MADE IN JAPAN"
Nil
Toshiba21 s
1.45 MB/s
Kingston 1GB SD
"Toshiba SD-M01G
0514TJ9034L
MADE IN JAPAN"
Nil
Toshiba
20 s
1.53 MB/s
KingMax 1GB SD
"P01GS6GMHLLAG
651054"
18.8 MB/s Read, Maximum
15.4 MB/s Write, Maximum
Unknown
14 s
2.18 MB/s
Corsair 1GB SD 133X
"S51GBA0615KKKT7TWN"
21 MB/s Read, Maximum
15.5 MB/s Write, Maximum
Skymedi
13 s
2.35 MB/s
Toshiba 2GB SD Class 4
"Toshiba SD-M02G
0642TK8283U
MADE IN JAPAN"
4 MB/s Read and Write, Minimum
5 MB/s Write, Maximum
Toshiba
17 s
1.79 MB/s
Toshiba 2GB SD Class 6
"Toshiba SD-F02G
0706TL1531V
MADE IN JAPAN"
6 MB/s Read and Write, Minimum
20 MB/s Write, Maximum
Toshiba12 s
2.54 MB/s

As we can see, a faster card can help the K100D to write faster. However, the increase in performance is not as significant as it should be for such a very fast card used, e.g., the Toshiba Class 6 SD card rated at 20MB/s maximum write speed. Indeed, the K100D still writes rather slowly no matter what card used in it and it is indeed considerably slower than any of the DSLRs on the market. To compare, below are the results of the already slow Nikon D50:-

http://www.robgalbraith.com/bins/multi_page.asp?cid=6007-7905

But yet, the D50 is still relatively faster than the K100D.

Actually, if the same cards are put into a faster DSLR, there will be a huge difference in the write performance:-

http://www.robgalbraith.com/bins/multi_page.asp?cid=6007-8531

Do note that I have carried out my test with a very similar method as Rob Galbraith did and thus the results are quite comparable, I think. I shot 3 consecutive pictures in RAW and the read/write LED lamp's lit-up time is counted, by a stop watch and then the throughput rate for the write speed is calculated where 1MB = 1024^2 Bytes.

It is interesting to note that the claimed Class 4 "guaranteed" write speed by Toshiba according to the SD Association definition for a Class 4 speed card is actually somehow meaningless as the K100D is an example of such a slow device in which a 4MB/s rate can never be reached, so does the Nikon D50, too, although it is somewhere nearer.

In fact, the speed ratings of those SD cards are something that can never be totally trustworthy. In contrast, cards that are not rated may not be really slow, for example, the old Lexar ordinary 1GB SD card (bought in early 2005) has really given me quite a big surprise. It is actually quite as fast as the latest Toshiba 2GB Class 6 card rated at 20MB/s write speed (equivalent to 133X for the pre-"Class" representation), although it is actually not rated in any way.

Thursday, March 29, 2007

An Interesting "Unfair" Comparison: 5D Vs K100D

Here is a recent interesting head-to-head comparison for a Canon 5D against a Pentax K100D:-

http://www.dchome.net/viewthread.php?tid=335580

(The original post is in Traditional Chinese, use Babelfish if needed.)

To make the test even much more unfair, the tester used a Canon 24-105 L lens on the 5D whereas a slow and long range Sigma digital superzoom 18-200 was mounted on the K100!

As it is stated in the beginning of the post, the difference in prices between the two comboes is four times! Someone did respond to the thread that it was considered to be "not making sense at all!".

But let's view the pairs of the test pictures objectively, then I think this test is actually very meaningful. Indeed, we can see how Pentax and Canon produces pictures which can look differently and in what ways they are looking different.

Before going on for what I have observed, you can first see the differences yourself carefully by inspection.

For what I can see, it is found that the resolution of the 5D pictures is much higher, there are more details in the pictures no matter viewed at full size or cropped. The colours are more eye-catching, especially for the reds. The bokeh are obviously nicer. The Canon pictures look brighter. Clipping of highlights are less obvious and the bright area transitions are smoother for the 5D, even for where highlights have already been clipped (that would be very obvious for the Pentax, just see the white sky for one of the test shot pairs).

But is that really that the Canon produces absolutely better images than the Pentax? I'm afraid not, against what most people would think. Actually, I don't like Canon's over-manipulation of the brightness tone curve where the highlight areas are with steep contrast curve, locally and regionally along the levels, and they are intentionally lifted to a higher level than it originally should be. As a result, one can see the highlights are quite bright and I would use the word "glowing" to describe. However, just take the example of those white or light coloured buildings in the test shots, I'm sure one would never be able to see such "glowing" buildings in *real-life*.

Furthermore, the Canon pics are with highly saturated colours and that there are actually more sharpening applied.

Both of the above ways of "processing" will actually make the Canon images not quite natural. Indeed, I can say the Pentax produces more natural pictures than the Canon. If a better lens is used, I'm sure that one must able to see better or even the best results.

Anyway, I know many people would like to love to see pictures which are with exciting colours, sharpness, brightness and contrast. But then whether these reproduced images are true to life and natural would be another problem :-)

Do note that the tester did set -1 for the contrast for his K100D, which I think it is the main reason for the lower contrast seen in the pictures taken with the K100D. Anyway, I think the tester should have a good reason for doing so, maybe he found that his Sigma lens was too contrasty, just say. Also, btw, the Sigma lens is not that bad as seen in the pictures, especially consider that it is a Sigma but yet the colour rendition is still okay.

Sunday, March 25, 2007

Unfavourable Colour Response of Quite Some Recent Pentax Lenses

Since I owned my D-FA 100 Macro lens two years ago, I found that it often produced colours which look somehow strange to my eyes. Such unfavourable colour response is simply something which I don't like, maybe personally, but, it has never been seen by me before for any previous original Pentax lenses, especially for Pentax primes which have been renowned for decades for their rich but yet accurate and natural colour rendition.

Indeed, the unique favourable colour response of Pentax's optics *was* one of the top reasons for "why Pentax?". However, this unique Pentax character seems to have been got lost for quite some of their latest lenses since the Tokina-Pentax "Co-development" era and/or since the "Lens Made in Vietnam" age. Another top reason to go with Pentax have been their superb and unsurpassed flare control of their lenses, it still holds true for most of their current products, yet very fortunately.

To describe more about the "unfavourable colour response", the problem is that pictures happened to have WB (no matter for Auto or Manual) wrong more frequently but even though the WB is correct, pictures look cool plus usually the green and blue colours are looking odd. Skin tones are not looking good neither. Scenes and landscapes are looking unnatural. (So, what application would the lens is ideal for?) There is usually kinds of blueish and/or greyish tone on the images, which is hard to describe. For green colours for trees and leaves, an overlaid yellow tone could be seen.

Here are some examples (of mine):-



(All pictures were shot in RAW and with some amount of +ve digital compensations when converted to Jpegs to compensate for the underexposure and no other adjustment was made, except for the last one of which the WB was also adjusted as the AWB was seriously off with very strong orange cast for the recorded RAW.)

It should be further noted that the same observation of mine holds true for all the Pentax DSLRs I have used, when I compared the D-FA prime lens against other older FA primes or even zooms, for the same camera body used with the different lenses.

Actually, you can view quickly the brief EXIF info, which I have preserved in the above downsized pictures, I recommend to install this extension for Mozilla web browsers. To view the pictures in large size, just click on them.

To compare further, I have selected a set of similar macro photos with my "digital optimised" D-FA lens against an older FA Star lens, first see the following recent photo of mine which I took last month, for a little bee, with my K100D:-

http://www.geocities.com/ricehigh/Gallery/Macros/IMGP1779s2.jpg

Indeed, I took the picture under direct sunlight in RAW and the original RAW file did sufffer from very strong yellow/orange cast. Ditto for quite some flower shots which were taken at the same time. This is not an AWB problem as even I chose the standard "Daylight" setting in the Pentax Photo Lab (the original bundled RAW convertor), it still didn't help. So, I corrected it using the grey point tool. In fact, I have never experienced similar problem(s) with any of my FA primes for similar shooting environments, i.e., the colours are right mostly at the first place when shot under sunlight as recorded and no significant re-touching was required!

To compare and to see what is the true Pentax quality on colour rendition, anyone can look at the samples below, which were taken with a FA* 200 Macro, especially for the excellent rendered colours. The pictures were taken with a K100D too, which I must say is the best Pentax DSLRs up till now for the colour response (Sorry, not the K10D, IMHO):-

http://www.dchome.net/viewthread.php?tid=335159&extra=page%3D4

BTW, some people may ask: What's the big deal? ..even if you yourself don't like the colour reproduction of a *particular* lens . . .

But what I wish to point out is that the mentioned strange colour reproduction is NOT an isolated case for *recent* Pentax lenses in the *current* "digital" lineup. It is indeed a common "problem" in my opinion, especially for quite some of those more expensive ones! (but Why?) First see this (terrible) sample photo below, which is posted in the latest K10D review of Steve's Digicams, which was taken with a DA 70 Limited:-

http://www.steves-digicams.com/2007_reviews/k10d/samples/IMGP0888.JPG

Once again, I can see the unfavourable colour response which I have mentioned above and this one is actually very exaggerated for the undesirable effect. Well, and, that undesirable effect is exactly of the same "style" of what is being described and shown here (but the effect is even more dominant).

Well, again, to compare, we can have a look on another picture taken for the same scene in Steve's K100D review, this time with a DA 21 Limited:-

http://www.steves-digicams.com/2006_reviews/k100d/samples/IMGP0352.JPG

What I would say is that the colour reproduction of the DA 21 Limited is right on the K100D and it is what a *Pentax* lens should produce in my mind. Although the picture was taken in the "Bright Mode", I can guarantee that the huge difference you see is simply not because of this and I can surely tell that the Bright Mode can only make things worst if there is any colour cast or any unfavourable colour response! It is just because the Bright Mode exaggerates colour saturation and brightness and if there is a colour problem, it will be shown up more clearly. Although one may still argue that the weather and lighting conditions could be different, I would say the big difference in colour response can be seen clearly, already. Also, I think that an experience reviewer like Steve would not be stupid enough to shoot a sample photo in bad weather or poor lighting conditions, would he? I bet he does know how to take nice looking sample photos for his review afterall.

Recently, Ned Bunnell has posted a number of the DA* 50-135 sample photos at his blog:-

http://nedbunnell.blogspot.com/2007/03/test-photos.html

Unfortunately, I found the same problem in most of his photos and I don't like the colour response neither. As Ned's sample photos should be considered as more than semi-official, I must be "convinced" this time!

Ironically, I must mention about that the same problem has *never* been found with the $60 kit lens DA 18-55/3.5-5.6 which I have already got two copies of it together with my *ist DS and K100D. The colour reproduction is of the old Pentax style which is very nice, although this kit lens's colour rendition is somehow over-saturated and exaggerated, but it is still "correct"!

So, at least, the good thing is that there still exists *some* recent Pentax lenses in the latest Pentax digital lens lineup that are right inside and are having the true Pentax image quality in the colour rendition department, e.g., the DA 21 and the kit lens DA 18-55. But unfortunately many others in the lineup seem do not, and even more unfortunately, those are usually upper class ones! (which required "co-development"?)

I don't know if there are some other people who will like or even love the "new" colours, but I'm sure I am not and will not be the one and so do many other people, I bet! The most worrying thing here is that the "new" colour representation seems to be the future way to go with the latest and coming Pentax lenses! Oh, No! Please.. I cannot really accept this trend, but, it seems to be the reality!

P.S. When people will probably ask me again, "What's the fuss about?", then I shall probably ask back the main question, "Where has the true Pentax character gone?" :-( Well, of course, I refer to the unique and favouable optical character here, especially for the colour rendition department, but, those were the days..

Read also:-
Scary Tokina 16-50/2.8 Official Sample Photos

RiceHigh's Subjective Ratings on Pentax Lenses on Pentax DSLRs

Friday, March 23, 2007

A Virtual Lens Plant!

Here is an interesting virtual lens plant on the net where you can see how a lens is built and made, from raw materials for making glass, building of glass elements, to the assembly process:-

http://web.canon.jp/Camera-muse/tech/l_plant/main.html (Japanese)

http://www.canon.com/camera-museum/tech/l_plant/main.html (English)

Well, as we can see, the lens plant is so labour intensive and I couldn't imagine before how manually the lenses are assembled and skilful workers with great care of works are indeed a must for good workmanship. It can be seen also that for each manufacturing process, QC and different inspections are carried out by the workers during the process along the production line. Well, there is a final inspection for the whole lens at the end, but the quality inspection and checking for *each* step is crucial.

I now know that why those various Canon lenses which are made in Japan are so expensive, as the labour costs are so high as the lenses are built in Japan locally.

While Pentax and Nikon have already transferred most of their lens making facilities and plants out of the Japan to Vietnam and Thailand respectively, it seems that Canon insist to build their mid to higher grade lenses in their Japan home despite that this will lead to high prices of their lenses, which make their product less competitive price-wise. But I bet Canon should have their own reasons for their insistence.

On the other hand, the main reason to migrate lens plants to South East Asia is clear. It is obviously aimed at the saving of the overall manufacturing cost since the huge labour costs involved can be significantly reduced by doing so.

From a consumer perspective of mine and my own experience with (Pentax) lenses made in Japan against those made in elsewhere, I can say those lenses made in Japan are undoubtedly with better built and quality (which hints at least a better quality control and assurance). But then Pentax lenses which *were* made in Japan in the past, instead of in Taiwan or elsewhere, are of a higher class or even luxury grade, so it would be somehow unfair to compare.

But on the other hand, the consumers could buy lenses at a cheaper price which would be impossible in the past, possibly at a lower (but not a *much* lower) prices, as far as I can see for some lens models (but not all, e.g., the new DA Limited lenses, which are indeed slower in speed, but the prices are comparable as the classic FA Limited lenses).

Now, when all Pentax lenses in current production are made in Vietnam (AFAIK, please correct me if I'm wrong, but preferably with evidence), I don't know if we could still spot the difference, as I did in the FA era, anyway.

Also, does anyone know if the coming DA* (Star) lenses will be made in Vietnam (as all those current other digital lenses of Pentax) or Japan (as their old film FA* and Limited lenses)? Anyway, I bet they will be / are being made in Pentax's large new lens plant at Vietnam which Pentax have put huge investment to the plant (according to the previous news reports one to two years ago) and that the current DA Limited lenses are made in Vietnam already.

Let's wait and see.. (all about the lenses' actual quality and performance, as well as where they are made and etc.)

Read also: RiceHigh's Pentax Blog: Where are the Pentax DSLRs and Lenses Made?

A Shootout between Dust Removal Systems

Here is a systematic shootout between the four dust removal systems from Pentax, Canon, Olympus and Sony, for the K10D, 400D, E-300 and A100 respectively:-

http://pixinfo.com/en/articles/ccd-dust-removal/

I won't particularly comment further as the review article above is self-explanatory. The test results are quite distinct and I must agree with the conclusion made.

Nevertheless, what the test tells match exactly with my previous research findings about the (in)effectiveness of the Pentax's DR system used in the K10D:- RiceHigh's Pentax Blog: Reports on In-effective Dust Removal of K10D Continue. The stories coincide.

So, next time when certain Pentaxians are still asking me, "What's the fuss about?", for what I report, I think anyone would better to see all the provided information and evidence first, before one is to ask a similar question, or even to over-react. :-)

By the way, Pentax do have some real DR solution themselves. I bet the reason for why they put a Sony A100 DR "solution" clone in their K10D would be purely owing to cost and time concern which required nearly zero for both as the AS/SR system is already there and ready to "shake off the dust", but actually it is something "useless" as verified. Whilst some Sony and Pentax users are very disappointed, I'm afraid that the original marketing claims turn into market lies in the eyes of those disappointed users, indeed.

Okay, let's have a look at the potential real thing from Pentax, which of course will need additional facilities to do the job, as there is no free lunch on Earth! Here is a Pentax filed patent:-

http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=JP2005354330&F=0

As you can see, the method uses suction air to remove dust particles out of the camera body, completely. I bet it will be close to the effectiveness of using an air blower, which this level of cleanness will undoubtedly surpass the existing Olympus design, as seen in the shootout experiment above and it has been shown that air-blower is a very effective mean for removing dust particles. Nonetheless, the perfect cleaning is still only achieveable by wet cleaning, i.e., swapping the sensor with cleansing fluid.

Wednesday, March 21, 2007

Which Flash Units are Safe for Pentax DSLRs?

Do you have an old flash unit that you want to use on your Pentax DSLR? Do you need to buy a new flash gun for your Pentax DSLR for whatever reason but wish to consider an alternative other than Pentax dedicated ones (now only the AF360FGZ and AF540FGZ which exclusively support the Pentax K series DSLRs)?

Actually, the two main concerns by the users are:-
1. Will they work? (and how good do they work?)
2. Are they safe to use? Will the flash units damage the camera body?

For the first question, my answer is that *normally* they will work, i.e., the DSLR body can control the flash gun to fire, when the shutter is opened. On the other hand, for how good those flash units will work, it actually mostly depends on the quality of the flash units and how good they are designed and built for the performance aspects, e.g., exposure accuracy.

For the second question, before going further, I think everyone should read this page to begin with:-

http://www.botzilla.com/photo/strobeVolts.html

So, for the "flash trigger voltage" mentioned, it is simply the voltage that appears across the electrical pins of the "positive" and the "ground" of the flash unit's foot *when* the circuit is opened (at the hotshoe), before the flash unit discharges (when at the hotshoe the circuit is closed, i.e., switching on).

So, how to measure this "trigger voltage"?

Just see this for the detailed illustration:- http://www.botzilla.com/photo/g1strobe.html#danger

In short, it's very simple to measure. Just use a voltmeter to measure the voltage across the positive central pin (corresponding to the largest contact on the hotshoe) and the ground(s), i.e., the metallic contact(s) at the side(s) *inside* the foot of the flash unit's hotshoe stand.

But there are something more to note when doing the measurement, which is not mentioned in the above article, in order to obtain the most accurate results:-

1. Fresh batteries should be used, as later on you can see battery voltage could affect the trigger voltage of some flash units, quite significantly, usually for those old types;

2. Use alkaline batteries, which are of around 1.5V when new, so as to measure the possible highest trigger voltage out of the flash units;

3. Ensure hard press of voltmeter's probes to the metal pins of the flash unit so as to ensure very good electrical contact so as to avoid any possible drop in the measured voltage;

4. Be sure to turn on the flash unit during measurement;

5. Be sure to measure the trigger voltage as soon as possible when the ready lamp is lit (so as to avoid possible further self discharge which will lower the measured voltage - some designs would not continuously recharge the flash once the "ready" threshold has been reached).

For what I have measured for my Pentax AF240FT, a Canon Canolite D and a Vivitar 2800, the trigger voltages with a new set of Panasonic Alkalines are 2.7V, 185V and 180V respectively. If I replaced a set of freshly charged Sanyo 2500 mAh NiMHs, the measured voltages are then 2.7V, 165V and 160V respectively.

It is interesting to note that my year 1988 AF240FT dedicated Pentax AF TTL auto flash gun (1st generation of its kind) does have some kind of regulation of the trigger voltage which is extremely stable, regardless of the battery voltage and status. On the other hand, my 1978 bought Canolite D and the plainly old designed and inferiorly built Vivitar manual-set auto flash both do not have any kind of voltage regulation nor voltage suppression so that the trigger voltage can be very high at 180 or 185V DC!

So, let's come back to the Pentax (DSLR) case. Can all those different types of flash guns work on Pentax DSLRs? My guessed answer is Yes. They will work *as long as* *both* the camera and the flash are working together! ;-) I have had no problem in using any of the above three flash units on any of my three different models of Pentax AF film SLRs and another three different models of Digital SLRs. But anyone should be aware of the excessive trigger voltage which *might* damage the electronic controlled switching part of those newer electronics cameras (not only Pentax ones), as explained in details in the last quoted article, here.

All in all, what we *first* need to check is: 1. the trigger voltage of your flash unit(s) in doubt and; 2. the maximum voltage which the newer Pentax DSLRs can tolerate. (Note that I have highlighted the word *first* above and I shall explain more in details for what does this mean :-))

For the various different trigger voltage values measured by various different users of the net community, we can browse through "the strobe list" summary table in the following page:-

http://www.botzilla.com/photo/strobeVolts.html

As for the maximum toleratable "safe" voltage of the Pentax DSLR bodies, *for long term usage*, it remains a mystery. But it can be seen in the following discussion page for some of the reported cases, in which some reference information can be found:-

http://www.botzilla.com/photo/photoBook/pbook.html#msg200

"Pentax (germany) informed, that the maximum-voltage for DSLR's *istD + *istDS is 30 Volt
Positive in the middle."

"I checked a new Vivitar 285HV with Quest rechargable batteries and got 13.31 volts. I have burnt the sync out of two Pentax AF bodies in the last year."

So, if the first claim is true, then the Pentax DSLRs are actually ISO 10330 compliance. However, since there is also user report of burnt camera for using a flash unit of trigger voltage at such a lower voltage of 13.31V, I think we should be more susceptible to the potential hazard here. As long as the trigger voltage is concerned, I think it would be safe enough to check the maximum trigger voltage amongst all the original Pentax units in the trigger voltage summary table, as the bottom line. It can be seen that the highest voltage reported is 7.8V, for the AF200/280T.

So, as all Pentax original flash guns should be safe to be used on any Pentax SLRs, can we assume that if we have a flash unit which has a trigger voltage lower than 7.8V, then it will be safe for use on our Pentax DSLRs? I am afraid that the answer is simply No, in contrary to what the author of the above "trigger voltage" page suggests!

Why? Still remember the thyristor capacitor for the switching job for modern SLR bodies? Actually a thyristor is an electronic device. Any electronic device has a maximum tolerance on the voltage, but also the *current* and thus a theoretical maximum power that could apply to it before it could be permanently damaged or when it refuses to work temporarily. The same even applies to mechanical electrical switches, although the maximum ratings can be (much) higher.

It is therefore checking the voltage is the first thing to do and actually it is the easiest and simplest to check. However, if the current is over, that could still damage the thyristor component if it is out of the maximum toleratable value. So, afterall, I would recommend it is stll the safest to use only original Pentax flash guns on Pentax DSLRs, even though we have only two choices (of two models) up till now (and very soon there will be three - but with a new useless model added, which is underpowered and rather crude to be useful) and despite that all the older Pentax TTL dedicated auto flash will have no auto control function on *any* of the Pentax K series DSLRs.

Nonetheless, if you still wish to take the risk by using any non-Pentax flash unit on your Pentax DSLR, do at least try to measure the trigger voltage and see if it is not more than 7.8V. Do note again that the author of my quoted page does warn about the potential damage to our cameras for long term use of a high trigger voltage flash unit on them, anyway.

Sunday, March 18, 2007

VPN and HPN / Bandings of the K10D

Here is an interesting recent experiment carried out by a Pentax K10D user who attaches the vertical battery grip D-BG2 on his K10D:-

http://www.carpelux.net/cat/vpn-hn

It is found that in addition to the "usual" Vertical Pattern Noise (VPN) , there is also Horizontal Pattern Noise (HPN), which the author has verified in his experiment and that it is confirmed that the HPN is simply caused by the battery grip when it is turned on.

Whilst people recently like to use the term VPN when they referred to the problem, previously the term "banding" was more commonly used when this was referred. Now I would refer both the VPN and HPN collectively as bandings, no matter they are vertical or honizontal ones.

In this article, I shall briefly look into the technical reasons behind for why there are the bandings, and, could firmware cures this problem or not, fully or partially.

Before going on, it would be good to see one more recent illustration of the VPN and HPN problem:-

VPN has a nasty friend!

In January, Pentax released a new firmware version of 1.10 which they claimed that "In rare case, vertical stripe at long time exposure." as one of the two corrections contained in the firmware. Pentax did acknowledge the problem and they did take the measure, which is a good thing, IMHO. However, the attainable correction amount purely by software (firmware) and the effectiveness of this solution is yet unknown, and actually is questionable, I would say.

To know for a *brief* explanation of such banding, here is the offical answer from Nikon, for the cause of vertical banding seen in some of their D200 units. But as we can see, Nikon offers free adjustments for users who found the problem and they are required to take back their D200 back to Nikon for servicing. Thus, this would imply it is a hardware adjustment or at least a low level firmware parameter setting by some kinds of "factory" calibration which is something impossible to be correctable at the user level, including a simple firmware update.

For comparatively more technical explanation, here is what Ken Rockwell says, which I think is clear and correct. To supplement what he says more in depth technically, we can have a look on how the CCD imager in our "CCD DSLRs" gets the image data and how it handles the signals for the image, at low level. Let's read back my earlier article about this:-

The Secrets of the K10D (Part 1 of 3) - The Heart: The CCD Imager

Unlike CMOS, any CCD needs to clock out chains, further by lines, of image data by channels (same as chains). So, each "clocked" line and *hardware* channel will have individual differences, as it is impossible they can be made identically. Particularly, actually the ADC need to determine the black level too for each clocked line but this black level value determinated is a variable. Especially when in extreme cases, the black level obtained can frustrate largely and it cannot be determined in an accurate way. There are a number of good technical reasons for how comes the errors, one of them is the "Smearing" effect, which you can find a good explanation in the following lengthy NuCore presentation, along with quite some other explanation on the causes and their cures of other digital image artifacts (Warning: Very Large PDF File!):-

http://www.nucoretech.com/nu3/images/80_downloads/pres_technology.ppt.us.pdf

So, banding is actually caused by the inherit limitation of how CCD works. To deal with this problem, different ADCs can have different *hardware* measure(s), depending on different design, which is then could or could not be catered with by the firmware. But undoubtedly, precise and accurate calibration is required so as to eliminate the effect as far as possible. Also, if the hardware and software are intelligent enough, the undesirable effect can be eliminated further.

Do note signal noise, no matter it is from inside of the CCD and/or from the ADC, or, from external interferences by other hardware, is the main culprit for causing *any* banding. So, it could be easily explainable for why when the user, whose experiment I have quoted in the beginning of this article, found that horizontal banding is caused by the switching-on of his D-BG2 battery grip. It is simply because the battery grip just cause some kinds of interference to the CCD/ADC circutiry which picks up the noise and finally shows up as horizontal banding.

To be fairly say about the comparison for CCD Vs CMOS, whilst CMOS imagers do not suffer from the banding problem, as the image data are picked out per pixel, they do suffer from the random noise which caused by the individual hardware difference per pixel! Yes, the difference is by pixel, not even by channel or by line! But if this could be eliminated and minimised by proper filtering and image processing means, which Canon succeeded to deal with this hardware limitation with their DIGIC processors and associated correction circuitries.

Also, just for the sake of a more balanced view and as a final remark of mine, I guess those bandings problem would be a non-issue for most of practical shooting cases, as it happens only when very high ISOs are chosen, say, 800 or 1600, and then when the user (or the camera) underexposes the scene, *and then* the user chose to push up the exposure by at least 2 stops, or more. THEN, you can see the bandings, no matter they are vertical and/or horizontal ones.

So, next time when you see minor bandings when you shoot under extreme situations and post processing in an extreme way, you should regard this as normal and should be acceptable, especially for a CCD camera. But when you see obvious bandings in quite normal shooting situations when you just use your camera normally at low light, maybe with just higher ISO without underexposing and/or push processing, I am afraid you have a poorly calibrated camera, no matter for the hardware and/or the hidden firmware parameters, then in such case, you should get your camera back to Pentax for a proper calibration and re-adjustment.

I hope my this short conclusion and recommendation can help all those users who frequently asked about the VPN, HPN, VB or HB questions from day to day, no matter which CCD DSLR model(s) you own, a Pentax one or not! :-)

Tuesday, March 13, 2007

PMA Disappointment (but there is hope)

The PMA has come to the end. As we all know, Pentax has only shown in the PMA two new DA* lenses with SDM (Supersonic Direct-driving Motor) AF support, for the first time, with a 645D behind glass and a new super simple Pentax dedicated P-TTL auto flash AF200FG (no zoom head nor it is movable in any direction and there is even no AF assistance spotbeam!), along with a few minor updates to their P&S DCs as their latest X30 models.

Nevertheless, Pentax has updated and published their new lens roadmap. The closest things which shall see the light are the two DA* super-telephoto primes and one zoom along with a 35mm/F2.8 DA Macro.

The biggest disappointment of this PMA show on Pentax’s part is that there is no new Pentax DSLR announced, which I guessed just right before the PMA. Whist the lens plan of Pentax seems to be quite aggressive and a truely complete lineup can be formed by 2008, I just wonder if the Pentax DSLR system can be successful without better DSLR bodies (and continuous upgrade of their current models).

While on these few days during the PMA I have posted in net forums that I think there should come a K100D and K10D replacement, preferably also with a new compact entry level DSLR plus a true high end / pro level DSLR model well above the K10D, quite some people have been arguing that there is no need to have new models for the time being, just because their current K10/K100D are “so good”. Today, I learn the good news that Pentax has actually planned to have updates on both cameras within this year, as well as they *would* consider another compact model and/or true pro level model (which they claim that they are capable of making one), in the following interview with Pentax senior officials at the PMA:-

http://dc.watch.impress.co.jp/cda/other/2007/03/12/5799.html (in Japanese)

and here is a human (not machine) translation of it:-

http://www.pentaxforums.com/forums/pentax-dslr-discussion/4337-translation-pma-pentax-interview-new-dslr-body-year-company-strategy.html

So, there is still hope, although there are so little DSLR stuff shown or announced in the PMA, which is quite a disappointment indeed. At least, we shall see that the K100D will be replaced not later than July this year and the K10D will be replaced by November this year. And, there may be surprise on a new compact model, too! But, I bet the new pro level DSLR will be unlikely to see the light in the near future, yet.

It seems that Pentax is now in a right direction for what they think and planned to do, from what I can see in the interview, let’s wait and see!

Thursday, March 08, 2007

Scary Tokina 16-50/2.8 Official Sample Photos

The twin-born lens of the Pentax DA* 16-50/2.8, the Tokina ATX Pro 165 DX's official sample photos have been out:-

http://www.tokina.co.jp/d_slr/index.html

However, these are some of the most scary sample photos I have ever seen, in terms of the image quality, technically, no matter it is official or not.

All in all, I must agree that these are with "totally embarassing technical quality" and "the most ridiculous photo sample presentation ever" as Klaus Schroiff and other folks thought and discussed here.

BTW, do note that the sample pictures were taken with a Fuji S3 Pro, which should be a very good DSLR in terms of image quality. The images were up-sampled to 12MP, though. To view in the original 6MP native resolution of the Fuji SuperCCD, one can view at 70% to see if the evils are still there!

Tuesday, March 06, 2007

K10D New Firmware Version 1.11

A new K10D firmware version is released today and it can be downloaded from the following link, at Pentax's Japan website:-

http://www.digital.pentax.co.jp/ja/info/20070123e.html

For a glance at the "changes" for this minor firmware update, I really have no idea on what those changes are talking about:-
"1. Correspond to development in the RAW data camera when multiple exposing."
"2. When built-in flash is used the luminescence control by the trailing-shutter-curtain sync was corrected."

Are those about debugging of some existing bugs or simply the correction of some known problems? Even they are, I don't really understand what are the problems Pentax Japan are trying to describe! Terrible English! Now I think my English is not really that bad at all! ;-)

Friday, March 02, 2007

When 1100mAh Li-ion RCR-V3s Outperform 2500mAh+ NiMH AAs ..

Backgound

As you may know, all Pentax DSLRs except the K10D adopt the “AA battery solution”, that means that those DSLRs only accept single-use disposable or rechargeable batteries in either AA or CR-V3 format.

K10D is the first and the only Pentax DSLR up till now which uses proprietary Li-ion rechargeable battery, which is the right thing to do, IMHO, but indeed Pentax responded too late and too slowly as the infamous Pentax DSLR battery issue/problem has been dragged on for so long since September 2003 with their *ist D to even up till now, for the K100D. In fact, there are still numerous different K100D users who are yet asking the related questions from day to day for the annoying problems they have encountered. Here is a recent example, which, for the first time, I could see a more concrete and sensible reply from a Pentax staff:-

http://forums.dpreview.com/forums/read.asp?forum=1036&message=22124985

Indeed, whilst the reply from the Pentax representative is true and this guy was indeed brave and helpful enough to tell the truth (which is absurd, however, e.g., try not to use the LCD as far as possible if one uses NiMHs, or, use CR-V3s which the DSLRs are designed for and etc.)

So, if NiMHs actually work like this and degrade the DSLRs’ performance and reliability so significantly, what other *rechargeables* else could be used by those pity Pentax DSLR users? The only solution left is the Rechargeable CR-V3s (RCR-V3s), which are made with the Li-ion technology.

However, do note that Pentax do state in their websites and newer user manuals that RCR-V3s should NOT be used in their DSLRs, “due to the voltage characteristics”, as stated. Indeed, the true reason for why Pentax do not want their users to even try RCR-V3 is likely to be that there exist non-voltage-regulated RCR-V3s which output “raw” Li-ion voltage, at around 3.7 to 3.8V per battery, which is just too excessive for their DSLRs which are designed to work at 6V, nominal.

On the other hand, for all other RCR-V3 models which are regulated to the lower voltage range close to 3V, i.e., similar to what those disposable lithium batteries would give, I can’t see how there can be any problem. The possible remaining factor would then be about the "internal resistance" of the battery, which constitute the *overall* characteristics of a battery (actually not just the “voltage characteristics” alone, which Pentax mentions about only) . But as Pentax have never mentioned about that it is the different internal resistance which would cause troubles nor actually there is any big difference in value of it when compared against those disposable lithium batteries. Again, the true reason for the banning of all RCR-V3s should not be with this factor.

BTW, I myself was able to find a good pair of RCR-V3 batteries with a very good charger (except that it only charges one battery at a time which causes some inconvenience and requires more time for charging two), after I had with my *ist D for a year, when I still could not resolve the annoying rechargeable battery issue with acceptable performance results with any of my Panasonic and Sony 2100 mAh NiMHs with original Panasonic charger or another not-so-famous brand charger named “Super”, which also working in the “negative pulse” charging principle (which the charging voltage is monitored to see when a negative change in the charged battery voltage occurs).

The two most annoying things of the problem were that the camera’s battery indicator shows most of the time that the battery is half depleted (thus the purpose of the battery warning is defeated) plus the camera obviously works slower as compared to when CR-V3s were used. The slower AF was most obvious, which still holds true for my *ist DS and K100D.

Ironically, at that time before I found the ultimate solution, I did use quite some of the methods stated by the above honest and helpful Pentax customer support representative, in order to save battery power when I used my NiMHs! Yes, I know that I can use my DSLR without the LCD turned on, as we used to shoot film, but why this is needed for a *Digital* SLR? And why we are forced to use our DSLRs in a film SLR way?? And, why I needed to use a DSLR without a low battery warning???

In contrast, since I got my RCR-V3s, all the problems were resolved and my DSLRs (include *ist D, DS and the K100D) with RCR-V3s in them perform as good as fresh disposable CR-V3s, except for maybe yet a shorter battery life, but they are rechargeables, not disposable anyway. The battery indicator does show the battery status correctly and accurately and that the AF speed is the same, most importantly. Furthermore, RCR-V3 batteries have very low discharge rate (versus that very high rate of the NiMHs), the built-in flash recharges faster and the Li-ion batteries themselves are lighter, too. Wow, there are just so many advantages with my RCR-V3s!

So, here comes the Question

Okay, let’s now back to the original subject title:-

When Rechargeable CR-V3s (RCR-V3s) rated at 1100mAh used in Pentax DSLRs outperform the highest capacity NiMH rechargeables, say, those rated at 2500mAh to 2700mAh, do you know WHY?

And, do you know and do you know how come the DSLRs' performance and stability will be inferior when NiMH AA batteries are used when compared against Lithium batteries, no matter they are disposable or rechargeables??

The Answers

Before going on, we can first learn about briefly how rechargeable battery works, here. Having the most basic concept in mind, now that we can proceed with something that are more technical.

First, Let's have a look at the datasheet of the Energizer 2500 mAh NiMH:-

http://data.energizer.com/PDFs/nh15-2500.pdf

In the “Rated Capacity” of the battery Specifications, it is stated clearly by Energizer that the 2500 mAh rating was measured with a load which drew current at 500mA continuously with the battery discharged down to 1.0V. To explain the “mAh” unit in practical sense, it can be interpreted that the 500mA current can run for 5 hours before the battery voltage drops below 1.0V, which is called the “Cut-Off Voltage”, below which the (weak) energy delivered will not be counted.

Essentially, the mAh is an equivalent measure of the amount of charge that can be stored in a battery. Do note that the total charge is not equal to the total energy, i.e., to know the energy, the voltage should also be taken into account. I shall explain this in more details following this article.

From looking at the discharge curve for the 500mA load, it can be seen that the initial voltage can be as high as 1.4V but the nominal voltage, which is the voltage which appears most of the time along the discharge curve is around 1.2V (this is specified in the Specifications too). So, the total *energy* (not power) delivered can be roughly calculated, without integrating on the curve over the time, is: 1.2V x 500mA x 5 hours = 3Wh, per battery cell. Note that this “rough” calculation does match with the 2500mAh rating specified, as 500mA x 5 hours is exactly 2500mAh.

Actually, for high drain electronics devices which demand large currents, the total deliverable energy will drop, according to the curves for heavier loads. To calculate the exact deliverable energy is actually not difficult, it is just the total area under the curve by integrating the voltage values with time and then finally times the current in Ampre, then it is the energy. Again, for rough calculation without involving any statistical summation techniques (as the curve has *no* formula, it’s by measurement), the nominal voltage can be observed from the curve and used for the calculation.

Just take the maximum load of 5000mAh curve for example, the nominal voltage has been pulled down to 1.1V and that the cut-off at 1.0V occurred after approximately 0.4 hour. Thus, the total energy delivered is 1.1V x 5000mA (i.e. 5A) x 0.4 = 2.2Wh, or the total charge is only 2000mAh. So, in this extreme case, it is only about 70% of the much lighter load which draws 500mA, with the same cut-off voltage at 1.0V.

We all know that DSLRs are high drain devices, plus the cut-off voltage at 1.0V is indeed totally *not realistic* for Pentax DSLRs, which should be 1.25V instead. Again, I will explain in more details for how this value can be checked out later. In the mean time, just keep this value of 1.25V in mind, which is the true cut-off voltage when NiMHs are used in Pentax DSLRs.

So, before looking at how the 2500mAh energizer will discharge and when my K100D will shut off when using these battery. First, we shall look at how my RCR-V3s discharge in my K100D:-

Initial voltage for a freshly charged RCR-V3 of mine is measured to be 3.4V with no load. Nominal voltage of each is measured to be 2.8V during the full use per charge, when loaded with a simulated load (which discussed more about this later). The cut-off voltage of the *battery itself*, with load, is measured to be around 2.5V, which is the same as the cut-off voltage of the K100D (again, this will be explained later for how it is found). In other words, the batteries already cut off themselves when the camera shuts off. Thus, every drop of the rated 1100mAh battery juice can be used. Thus, the total deliverable energy in the camera is 1100mAh x 2.8V = 3.08 Wh. Thus, two of the RCR-V3s means a total of 6.16Wh energy deliverable, in total.

Do note that the nominal voltage of 2.8V is 100% safe and fine for the Pentax DSLRs as the initial no-load voltage of disposable CR-V3 can be as high as 3.5V whereas the nominal voltage is rated as 3V, and actually is again something from 2.5V to 3V with a heavy load like the K100D, as seen in this Energizer datasheet and specifications of their CR-V3. Furthermore, in the above I have used the rated figure of 1100mA regardless of the current load. It is because for lithium batteries, the mAh will not be greatly affected as NiMHs do. To place safe, I have verified for this also. Just refer to the above CR-V3 datasheet again, it can be calculated that the total mAh figures for the four curves for the four different loading conditions are all around 3000mAh (which is the rated capacity of the battery), although for heavy load the nominal voltage will drop somehow practically (which means that less energy will be delivered, but the total charge usable will be the same). I won’t go further for the detailed calculations for these, though. But you can try it out yourself if interested, it’s not so difficult to obtain the results afterall.

Normally, I can attain 200 to 300 numbers of shots per charge with my RCR-V3s, regardless of the storage period. So, I take 250 shots as the figure. So, to calculate the average energy spent in each shot, the total deliverable energy stored in the pair of RCR-V3s can be divided by 250 first.

Here it goes: 6.16Wh / 250 = 24.64 mWh. With this 24.64 mWh energy, the camera performs all the tasks executed by the user. Some internal functions of the camera, especially for a DSLR, will eat away extra energy without the notice of the user, e.g., the driving of the CCD imager, LCD, ADC, IPU, CPU for general control function, memory card read/write (say, shooting RAW will use more energy), mirror up/down, aperture blade movement, and etc. Yet, other obvious "external" functions of the camera like AE metering and AF, or even the SR, still consume much energy.

So, with this 24.64 mWh, for each shot, if the DSLR does the job faster, more current will be drawn. On the other hand, if the camera does the job slower, less current will be drawn, but the time for completion of all the required tasks will be longer. I myself will not go further to measure the current nor the timing per shot for my typical usage pattern which actually would require a power analyser which can measure the current in ampre (and all other parameters like voltage, resistance and dissipated power as well) and plot it over the time (of course conduction wires are required to connect in between the camera and the batteries, in series, as the analyser is now an ammeter). So, to make the case simpler, here is a best estimate on the average time required per shot for my usual shooting habit / operation sequence:-

Setting the camera for 5 seconds; AF and AE another 5 seconds, take the shoot for 1 second, instant review for 3 seconds (as set as default), playback review for 5 seconds, plus, other camera's delay in processing and memory card read/write: another 3 seconds => total time required is equal to: 22 seconds.

So, we can now estimate the *average* current consumption of the K100D, we can divide the energy by the nominal loaded voltage and then by the time in hour, i.e.: 24.64 mWh /5.6V / ( 22 s / 3600 s/h ) = 720 mA.

And hence, the *average* resistance of the K100D is estimated to be 5.6V / 0.720A which is equal to 7.78 Ohms.

Now, if we are to compare the NiMH performance, to be precise, we can use this resistance value of the K100D. The practical implication of such a resistive load is that it will draw less current for a lower voltage applied. As for the energy spent or the work done for a particular job, they should be similar, e.g., work done (energy used) by the AF motor, a lower voltage means less current and thus the same job will require more time to complete (as the total energy spent / work done is roughly the same), thus, it is doing the same job comparatively slower just because the power is lower. This actually explains why AF is noticeably slower with NiMHs than with lithium power sources. For those who haven't noticed the difference, just put on the lens cap and half press the shutter release button and just let the AF motor to focus the lens to and fro and the difference in speed between NiMHs against Lithiums can be observed .

Now, we can look back again at the discharge curves of the Energizer NiMH. So, the first thing is that we should decide on which discharge curve is closest to the case of the K100D for the amount of the current drawn. So, the calculation now is possible with we get the estimated resistance of 7.78 Ohms. Hence, the current can be calculated as 5V / 7.78 Ohms = 643 mA.

Well, now I am going to tell why I could use 5V as the total battery voltage in the above. Still remember the cut-off voltage discussed above (for the camera itself but not the battery)? Here is an easier way to measure the cut-off voltage of the K100D: Just shortly after the K100D with NiMHs cut-off and shows battery depleted, pick out the batteries and measured the voltage with a close enough low resistance load with the batteries (ideally should be 7.78 Ohms for four NiMH batteries, mine is of 4.75 Ohms, so I loaded two batteries with it only) and the on-load output voltage is measured. I thus was able to find out that the K100 is very sensitive to the 5V border line. I do the same for my both my CR-V3s and RCR-V3s, with my load on each battery, and still I got a close figure to 2.5V per battery, thus, it is of 5V again for two (R)CR-V3s!

For NiMH batteries, a 5V cut-off in the camera simply means a 1.25V cut-off voltage per battery cell. Do note the 1.25V is indeed a higher value than most typically rated nominal voltage of NiMHs (whereas some others are yet rated at 1.25V nominal) and this doesn’t make much sense at all for such a high cut-off voltage required (but I bet the Pentax engineers had no choice, as the power requirements of their DSLRs are so high – so that a further lower voltage may not be feasible for the circuitries and electronics inside).

With the cut off voltage border line at 1.25V in mind plus an estimated drawn current of 643mA, we can now choose which discharge curve to look into. The 500mA discharge curve is close enough, although it's still slightly lighter for the load. Now we can check *when* do the cut-off of 1.25V will take. It can be seen that it can last for just a little bit over 2 hours without touching the 1.25V line, according to the curve, i.e., the flat part of the discharge curve (shortly after 2 hours, it starts to fall).

So, the total deliverable energy for the “2500mAh” NiMHs (before the camera cuts off) is: 5V x 500mA x 2h = 5 Wh.

Now, remember how much energy is deliverable for the two RCR-V3s? It is 6.16Wh. So, even having give the advantage to the NiMHs for the lightest load of 500mA (amongst all the tested loads in the datasheet), the "1100 mAh" Li-ion RCR-V3s still outperform the "2500 mAh"NiMH AAs.

Indeed, the fact is that even before the cut-off, the NiMHs provide a low voltage which the camera is *always* working very near the border line and this is undoubtedly the stability of the camera is affected. Indeed, the battery indicator does tell this very clearly (as it won’t lie) and the half-depleted warning does often show up. Do note also that if the battery voltage just drops below the border line for incident, the camera will shut off. Despite that there might be some juice left, which could still be sucked out bit by bit after enough “resting” time is given to the battery (to wait the battery voltage to come up again). However, I think this is indeed impractical in the field. Under normal circumstances and practically, when the camera is shut off for the first time, the user will surely replace the rechargeables immediately, I bet!

To consider an even more practical factor, do note that NiMHs are actually the fastest self-discharging rechargeables in this planet. So, after storage of the battery for a few days, I’m sure that you cannot get anything near the ideal value of 5Wh calculated above, neither.

Until very recently, Sanyo and GP have been able to develop and market their new NiMH batteries called Eneloop and ReCyko+ respectively so as to tackle with the annoying fast self-discharge problem of the NiMHs. Despite the storage time will be lengthened without significant loss of charge over time, the output voltage of those batteries are still at 1.2V nominal, as the chemical used in the batteries are still NiMH. Also, the rated capacity is smaller now at around 2000mAh for both. From what I have heard, those new batteries seem to have a flatter discharge curve which might be more favourable to the Pentax DSLRs, for the killing weakness mentioned above. But still, the cameras are still working near the border line and the performance of the camera is greatly affected, even you use Eneloop, here is an example.

In addition and finally, do note again that the typical 2500mAh NiMH rating is measured based on a quite ideal operating temperature of 21 deg. C (general room temperature) and minimal load condition. With the further decrease in temperature, e.g. shooting outdoor in winter, the total energy delivered will be decreased further accordingly. And as we all know, Lithium-type batteries are superior for cold temperature and for heavier duty whereas liquid type batteries like NiMHs and Alkalines are rather susceptible for lower temperatures. Here is a comparison between the performance of Lithium and Alkalines AAs for how they could differ.

Indeed, I found that my K100D is just more power hungry than my *ist DS which is again more power hungry than the *ist D. The symptom is that the power is cut off faster for the newer than the older, which simply implies either the set cut-off voltage had been raised for each newer model or it would be the case that the power juice is drawn faster for the newer camera, even the cut-off voltage set is the same.

In real practice, I find that the only usable NiMH batteries of mine in my K100D now is the Sanyo 2500 mAh NiMHs, which can shoot less than 100 pics for my shooting style per fresh charge, and must be within just a few days, whereas my RCR-V3s are typically good for around 200 to 300 shots per charge, regardless of the storage period, as I have already mentioned above. The practical results agree in general with all my calculations and measurement described above, which are largely based on the detailed data and information contained in the battery datasheets.

The Conclusion

Well, for the K10D, I do bet, which is the latest model with the most powerful specifications of a Pentax DSLR ever, maybe even more power hungry than the K100D and thus it is very possibly that it is completely not viable to use the “AA battery solution” anymore. The “AA battery solution” in Pentax DSLRs was and is indeed a totally wrong decision by Pentax from day one and is simply a design fault, frankly speaking. I don’t know if it was a marketing decision which overruled engineering judgement or not, but undoubtedly, the outcome was indeed terrible.

To make the situation even worse, Pentax’s official “ban” on *all* the RCR-V3 batteries instead of compiling a Tested & Approved list of those which are actually working ideally in their DSLRs (which actually unleash the peak performance and ultimate stability of their DSLRs, instead, ironically), was and still is, another very wrong decision, which Pentax missed the boat again for an actually viable remedial action for their original wrong decision (and wrong design). The sad consequence is simply that most Pentax DSLR users have no reliable rechargeable batteries, of any type, which is also officially approved by Pentax, that they can feel safe to use in any of their “AA battery solution” DSLRs, nor the DSLRs are actually operating at their optimal performance, which originally they are capable of !

I really hope that similar tragedies won’t happen anymore to Pentax (and actually more to their users) in the future. *If* Pentax *could* really listen to their customers, admitted problems and reacted promptly and positively, they could have been a more successful company in the market, instead of struggling for survival like what they are doing now. Nevertheless, ideally, they should have prevented stupid problems from happened at the first place, honestly speaking (although they hadn’t for this case).

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Update (on March 4): Since I have been bashed by particular die-hard blind brand loyalists who are "very happy" with their AA battery DSLRs, since I published my this article and everything became personal in the end, I feel very obliged to point to some feedbacks of other Pentax DSLR users who have reported about the problem. Indeed, those reports appear extensively from day to day and are very easy to find. In the end, even those people who bashed me didn't/couldn't see any problem themselves, why they needed to stop others from reporting the problem and also needed to put hatred on me for what I had looked into the case and suggested a possible solution here?

To illustrate it is not an isolated case nor it is "the user's problem", I simply choose a recent thread at the Dpreview forum. It can be seen that there are so many different users who are desperated, upset and reporting the true experiences of their "own" case(s), just within such a single short thread. I opt to list out some of the relevant reporting posts below:-

http://forums.dpreview.com/forums/read.asp?forum=1036&message=21995874

http://forums.dpreview.com/forums/read.asp?forum=1036&message=21998777

http://forums.dpreview.com/forums/read.asp?forum=1036&message=21999849

http://forums.dpreview.com/forums/read.asp?forum=1036&message=22268467

http://forums.dpreview.com/forums/read.asp?forum=1036&message=22270755

Also, this user is right to the key point, for the sluggish AF as a result of low voltage owing to the use of NiMHs:-

http://forums.dpreview.com/forums/read.asp?forum=1036&message=22273382

It's very obvious that there exists a common problem of the "AA battery" Pentax DSLRs and that Pentax's customer support staff seem have no much to do and can do for helping the customers who approached them for the problem. For that those users who have found and reported the problem are being accused of having problems themselves instead (by those blind brand loyalists) is actually utter nonsense. And, for those who try every effort to bash a person who is actually trying to be helpful is indeed very silly, again. Afterall, for all those blind brand loyalists who always like to respond to me in a personal way would not help anyone, including themselves nor their blindly loved brand, I must say. I do bet that the only "achievement" they could attain is that they could possibly feel much safer and more comfortable psychologically themselves by (always) doing so.

All in all, I have never rejected the possibility of some users are "okay" with their *particular* AA battery Pentax DSLRs with their *particular* AA batteries in them, for their **particular** applications (e.g., there exists an user who have responded that he could use his Pentax DSLR with AA Alkalines with no problem, really amazing!). Yet, there is an issue, in general, undoubtedly!

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