Tuesday, June 24, 2008

Dynamic Range and (Background) Noise Tests of the K20D

Have just come across a test review of the K20D today and found it to be quite refreshing and non-typical (I like it!):-

http://daystarvisions.com/Docs/Rvws/K20D/pg1.html

I think the most interesting part of the review is the test for the K20D's DR (by the author) and the test for the background noise (quoted results by others) of the K20D. To make the published results meaningful, the results are compared with other current DSLRs like the K200D, (Canon) 40D and (Nikon) D60 and D300 and the K20D's precedor, the K10D, as well. As such, a better interpretation could be achieved and I do believe the comparisons are fair.

I like the DR test was carried out in a way that it is very simple but effective to obtain meaningful results. I also like the review is written in a way that it is concise but yet very useful for the information contained and shared. I particularly like that the author writes technical stuff in a way that are easily understoodable for laymen and does not make it look too difficult (for the readers to read and understand).

So, here is the DR test results as well as the background noise analysis and comparisons, which similar testings and information is by far could not be found on the net and I do highly recommend to read this page (even you don't read the rest of the review!):-

http://daystarvisions.com/Docs/Rvws/K20D/pg3.html

As I have said, since the author has explained things so good and clear, I won't explain further for the above. Go read yourself, I am sure you can understand fully (or at least mostly) and do get something! (in particular for those refreshing data/info which are not that conventional!)

Nonetheless and all in all, I've learnt from the review that the longly and highly praised "underexpose to preserve highlights" myth as emphasized and insisted by particular Pentax fans has been proven to be invalid for the K20D. Or at least it is not really practical for getting good to acceptable results even such an approach is taken, manually and intentionally, in more contrasty situations. Also, with the comparatively much less DR and actually very limited DR of the K20D, it is a real concern for its impact on image quality for the pictures produced with the K20D. Furthermore, a narrow DR will lead to exposure problems more often too, as either highlights or shadows will be scarified in more cases. And, as recommended by the author, he would rather opt to blow out highlights to keep shadow details with the K20D owing to the limitations mentioned above - see his review and article for his full reasoning (which I am fully agreed with).

2 Comments:

Phil doesn't agree said...

From DP review:
Camera (ISO 100)
Shadowrange HighlightngeUsablerange
Pentax K20D -5.8 EV 3.2 EV 9.0 EV
Canon EOS 450D -5.1 EV 3.6 V 8.7 EV
Sony DSLR-A700 -4.9 EV 3.9 EV 8.8 EV
Olympus E-3 5.8 EV 3.0 EV 8.8 EV
Pentax K10D -4.5 EV 2.8 EV 7.3 EV

RiceHigh said...

I don't know how exactly the DPR crews did their DR test. But as for this DR test posted, the author first exposed for the brightest part (or, just the highlight), recorded the lightness differences in various parts in the frame with an external light meter, and then finally got the Dynamic Range in which the recorded image parts were still found to be acceptable.

In fact, the test procedures of this DR test are clearly described and I do trust his results here.

At least, if an "exposing for the highlight" technique is adopted, the K20D doesn't show a wider but just a narrower DR here (even than the K10D).

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