A Quick but Full ISO Test by a New K20D User (Vs K10D too)

A Hong Kong Pentax user has acquired a new K20D at the street of Hong Kong and he has immediately carried out a quick test for checking the image quality and camera performance (variations) at all different ISO speeds and here is his post:-

http://www.dchome.net/viewthread.php?tid=470500&extra=page%3D1&page=5

(Text in Traditional Chinese, use Babelfish to translate if needed. Btw, the captions in the posted test images are self-explanatory and are in English.)

The first thing to note is that the K20D image starts to appear grainy/noisy at ISO 800 and in my opinion ISO 1600 is already very marginally usable. But if you compare the K10D images which are shot at the same time for the same object with the same setup, the ISO 400 image is somewhat more or less the same as the ISO 800 image of the K20D, which means that there is a considerably obvious improvement in the noise performance of the K20D when it is compared to the K10D, especially considering that it has nearly 50% more pixels than the K10D. Having said that, it should be noted that the ISO 400 noise performance of the K10D is in fact sub-par, which is also quite some K10D users and I have been talking about for a while now.

The second thing is that the user reported that the (Auto) White Balance is far more accurate than the K10D, even under tungsten lighting. The reproduced color balance is more faithful to the original subjects as he could see so far (way better than the K10D, as reported). Well, it might be that it is really true or it is just that he is still enjoying his honey moon period with his new toy, anyway.

But the third thing which I can observe is the dark and gloomy pictures, which actually nearly becomes an unshakeable symbol or even icon for Pentax DSLRs, *can* *still* be seen. The K20D pictures look just a little bit brighter, though (but it still looks dark, muddy and dull).

Last but not least, since he purchased his K20D body (only) at near HK$11,000 (about US$1,400), which I would consider simply too expensive to consider objectively as the much more stronger (in specifications) and faster (for its true camera performance, e.g., AF and shutter lag, etc.) Nikon D300 is also selling just at a price which is dearer by very little bucks.

Do note that Nikon's system is undoubtedly more comprehensive and complete than the Pentax's one and Nikon's flash system is renowned to be the most accurate and versatile one, too, whereas Pentax's P-TTL has been reported from time to time rather frequently on the Internet for its inaccuracy and inconsistency. Although the K20D can be different but I have no high hope as long as exposure accuracy department is concerned for the Pentax DSLRs, judging from the past experiences of the Pentax DSLR users (and now the new samples published by the beta and production K20D so far). Besides, as long as the AF system of the K20D is yet the SAFOX VIII (at least as it is called), which is infamous for unsatisfactory low light performance and accuracy, I don't think choosing the K20D is a wise choice when one can actually get a far superior and better Nikon D300 at nearly the same price.

In fact, I have just tried a D300 yesterday (not at shop, one of my friends has purchased his new D300 so that I could try it out at the field), the mirror action is so gentle but yet crisp and I am really amazed with its lightning fast short shutter lag which is noticeably even shorter than my Canon 5D (around 78 ms as measured by CAPA Japan and the Imaging Resource, best timing) which is again noticeably faster than my MZ-S (which is again just faster than *any* Pentax AF DSLRs ever made!). So, I just wonder except the old Pentax DSLR user base who are particularly eager to replace their old Pentax DSLRs (which the users might be rather unsatisfied with something), for those who are new, WHO will really choose the K20D in view of the comparatively poorer price/performance ratio? So, here is my bet: Unless the price of the K20D goes down significantly, the product and Pentax won't succeed. Or, people just go to get the Samsung GX-20 which should be (much?) cheaper and with the original SilkyPix RAW software package (and better user interface than the Pentax Photo Lab), too.

First K20D Production Camera Formal Test

PopPhoto has completed testing a production unit (yes, they mention it is!) of the K20D and the full test report has been published:-

http://www.popphoto.com/cameras/5112/camera-test-pentax-k20d.html

So, for such a formal test, of course our main concern is on the various measurement results which are obtained under their controlled lab environment, in their professionally set-up lab. Here is the direct link to the K20D lab test results page:-

http://www.popphoto.com/cameras/5112/camera-test-pentax-k20d-rugged-body-smart-controls-page3.html

In order to make the obtained results more meaningful, we need to interpret the results by comparing the results of other DSLRs in the "same class", i.e., the targeted market segment. As the K20D is priced somewhere near the Canon 40D, Nikon D300 and the Sony A700 (said also in the PopPhoto's article) and all are the latest offers from the four brands, it's just trivial and fair enough to compare them.

Specifications wise, putting aside the old 16-segment multi-pattern metering system in the K20D (which has the least number of segments in the industry) and that all other DSLRs has a more sophisticated AF system on paper, the K20D do have a similar specification close to the 40D and the D300.

In order to do a more systematic comparison, we need to have more controlled tested data of the other DSLRs above. Very fortunately, PopPhoto have already tested all of them in their previous issues, the direct links of the corresponding results pages are as follows:-

Canon 40D:
http://www.popphoto.com/cameras/4668/camera-test-canon-eos-40d-specifications-certified-test-results-page3.html

Nikon D300:
http://www.popphoto.com/cameras/4911/camera-test-nikon-d300-vital-statistics-test-results-page3.html

Sony A700:
http://www.popphoto.com/cameras/4724/camera-test-sony-alpha-700-vital-statistics-page3.html

Now, we can go on to compare the results aspect by aspect. I summarise the key performance aspect results above in the following tables for easy reading and our quick comparison:-

Table 1:- Noise

Camera	ISO 100	200	400	800	1600	3200	6400
Pentax K20D	1.22 (Very Low)	1.49 (Very Low)	1.76 (Low)	1.64 (Low)	2.6 (Moderate)	3.8 (Unaccepatable)	6.04 (Unaccepatable)
Canon 40D	0.8 (Extremely Low)	0.95 (Extremely Low)	1.15 (Very Low)	1.49 (Very Low)	2.0 (Moderately Low)	2.9 (Moderate)	N/A
Nikon D300	N/A	1.1 (Extremely Low)	1.2 (Very Low)	1.1 (Extremely Low)	1.4 (Very Low)	1.95 (Low)	2.83 (Moderate)
Sony A700	1.25 (Very Low)	1.3 (Very Low)	1.6 (Low)	1.7 (Low)	2.5 (Moderate)	2.7 (Moderate)	3.1 (Unaccepatable)

As we can see, noise wise the K20D is just loser here. At lower ISO speeds, it by no means can match the 40D and the D300 for their superior noise performance. At higher ISO speeds, it just always loses, even to the Sony A700 (which also loses to the Canon and Nikon).

Table 2:- AF Speed (in Second)

Camera	EV 12 (at ISO 100)	10	8	6	4	2	1	0	-1	-2	-3
Pentax K20D*	0.37	0.44	0.43	0.54	0.97	1.17	1.22	1.67	2.33	-	-
Canon 40D	0.38	0.40	0.46	0.49	0.54	0.58	0.61	0.84	0.98	1.20	-
Nikon D300	0.32	0.33	0.41	0.51	0.67	0.78	0.90	0.93	0.95	0.98	-
Sony A700	0.24	0.25	0.31	0.36	0.36	0.89	0.85	1.18	1.16	-	1.37

* Update (Feb 23): The timing figures are actually K10D ones and I have also corrected the figures above as PopPhoto have already updated their chart in the K20D test report. In conjunction, I have also made two minor changes in the second paragraph below accordingly. For more about the story, see the post made by Jack (the PopPhoto forum adminstrator) in the thread below:-

http://forums.popphoto.com/camera/board/message?board.id=11&thread.id=16705

Their main argument for using the K10D data is just that as far as they learnt from Pentax, the K10D and K20D share the same AF system and in order to avoid further "confusion", they opted to publish the K10D timing results after carried out some tests for verification. Anyway, I myself am not convinced with this "reasoning", though.


Well, as many of the Pentax DSLR users, especially for those who have compared their DSLRs of other brands side by side when they were using their Pentax DSLRs at lower light environments (including me), the lower light AF performance is just pathetic for *any* Pentax DSLRs, the K20D is of no exception, as it has been verified from the above same lab environment, again.

It should be noted that at EV -1, the K20D was simply nearly unable to focus at a rather lengthy time of 2.33s which is in fact impractical to use for the AF. Actually, no other DSLRs would ever require more than 1.37s to focus even at EV -2 and EV -3 where at such a dim lighting level there is simply no figure obtainable for the K20D as it is very probably that the K20D had given up already to do the AF job at EV -2.

Not even to say actually the AF systems of Canon, Nikon and Sony all are designed to have the f/2.8 AF sensors which cater for faster lenses for better AF accuracy when used with those lenses, mostly primes, which Pentax simply lacks such a design.

Table 3:- Other Measurements

Camera	Resolution (lines)	Color Accuracy (Average Delta E)	Highlight/Shadow Details	Contrast
Pentax K20D	2350 at ISO 100-400	7.98 (Excellent)	High	Normal
Canon 40D	2100 at ISO 100-1600	7.7 (Excellent)	Very High	Slightly Low
Nikon D300	2350 at ISO 200-6400	7.19 (Excellent)	Extremely High	Slightly High
Sony A700	2280 at ISO 100	8.9 (Extremely High)	Very High	Slightly High

The K20D seems to have high resolution on a par with the D300. However, at higher ISO, it fails to keep the high resolution figures which the D300 has been able to maintain. But since the K20D has more pixels than the D300, the results are somehow unexpected.

As for the color accuracy, the 40D and D300 both do better than the K20D whilst the A700 is worst.

However, for the preservation of highlight and shadows details (also commonly referred to the Dynamic Range or simply DR), the K20D comes last. The K20D has the most accurate contrast, though. Do note that normally a lower contrast would normally result for a wider DR. It is therefore the Nikon and the Sony should have the potential to yield an even wider DR range if the contrast is tuned down a bit.

Table 4:- Overall Image Quality (IQ) Grading

Camera	IQ at ISO 100	IQ at ISO 200-800	IQ at 1600	IQ at 3200	IQ at 6400
Pentax K20D	Excellent	Excellent	Excellent	Extremely High	Not Rated
Canon 40D	Excellent	Excellent	Excellent	Extremely High	Not Applicable
Nikon D300	Not Applicable	Excellent	Excellent	Excellent	Extremely High
Sony A700	Excellent	Excellent	Extremely High	Extremely High	Not Applicable

Well, I think the last grading is redundant, after we have gone through the results of all the above key performance aspects measured. :-)

Anyway, after reading all these, there is yet only one question comes into my mind: Could and should Pentax do better? Could they?? Actually, I really just start to puzzle.. ( but I still know that *Pentax* MZ cameras' AF are better - at least faster at low light! :-( )