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12-16-2008, 03:03 PM   #1
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k20d or k10d - which has better dynamic range

DXOmark.com gives k10d better dynamic range than k20D.
DPreview says k20d has better dynamic range.

Who is right?

And are they noticeably better than the k100d?

12-16-2008, 03:30 PM   #2
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QuoteOriginally posted by Michael Barkowski Quote
Who is right?
DxO is over confident in (arbitraily choosen) mathematical formulas. Unfortunately.

As a photographer, I cannot trust any rating scheme which gives aggregate ratings like:
K20D: 65.4/100 (ranks #16)
GX20: 68.7/100 (ranks #10!)
(based on RAW which doesn't differ from one model to the other).

On topic:
The way DxO defines DR is DEPENDENT on the pixel resolution (a 1 Pixel sensor would always win...). So, my advice here is to only compare cameras with identical #pixels or completly ignore the measure.
12-16-2008, 03:34 PM   #3
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QuoteOriginally posted by falconeye Quote
DxO is over confident in (arbitraily choosen) mathematical formulas. Unfortunately.

As a photographer, I cannot trust any rating scheme which gives aggregate ratings like:
K20D: 65.4/100 (ranks #16)
GX20: 68.7/100 (ranks #10!)
(based on RAW which doesn't differ from one model to the other).
Sure it does... The K20D uses PEF and the GX20 uses DNG

Actually, I mean that sarcastically, but without reading the reviews or ratings, that is probably the reasoning as flawed as that may be (they probably don't even realize you can spit a DNG out of the Pentax camera)
12-16-2008, 03:36 PM   #4
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QuoteOriginally posted by Michael Barkowski Quote
DXOmark.com gives k10d better dynamic range than k20D.
DPreview says k20d has better dynamic range.

Who is right?

And are they noticeably better than the k100d?
John Sheehy and GordonBGood calculated the DR of the K10 as over and above almost all DSLR's at the time.
Unfortunately VPN pretty well killed the advantage. The large increase in DR was attributed to the 22bit ADC, so was the pattern noise
dpReview dynamic range measurements have always been suspect by many.
K10 also had a sever cutoff on the high end. Once you hit it it was toast. Very severe blowouts.

12-16-2008, 03:43 PM   #5
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Just by my comparisons, which isn't scientific, I say my 20 out does my 10.
12-16-2008, 03:56 PM   #6
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You also have to factor in ISO. I've read reports the K20D has good DR until ISO400, then it decreases quickly as ISO goes up...
12-17-2008, 10:32 AM   #7
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All, thanks for the reality check
12-18-2008, 02:05 AM   #8
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QuoteOriginally posted by emalvick Quote
Sure it does... The K20D uses PEF and the GX20 uses DNG

Actually, I mean that sarcastically, but without reading the reviews or ratings, that is probably the reasoning as flawed as that may be (they probably don't even realize you can spit a DNG out of the Pentax camera)
That reminds me.... Is there any advantage to setting the Pentax to PEF as opposed to using the more standard Adobe DNG format?

Just curious...

12-18-2008, 02:09 AM   #9
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QuoteOriginally posted by pentaxmz Quote
That reminds me.... Is there any advantage to setting the Pentax to PEF as opposed to using the more standard Adobe DNG format?

Just curious...
Yes. PEF is losslessly compressed = you get more pictures on the card.
12-18-2008, 09:28 AM   #10
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QuoteOriginally posted by Erik Quote
Yes. PEF is losslessly compressed = you get more pictures on the card.
That's strange. On the PC, it's the other way around. PEF is not compressed, and DNG is losslessly compressed. PEFs from my K100D are 8-10MB, DNGs made with Adobe DNG Converter are about half that size.
12-18-2008, 10:47 AM   #11
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Either file format is *capable* of being compressed. But the *camera* will only compress PEF, not DNG (and models prior to the K10D did not even compress the PEF). You can create a DNG file after the fact using the Pentax software or the free Adobe converter, which can produced a compressed DNG as output starting from either PEF or DNG.

I think a lot of people - myself included - shoot PEF simly to fit more images on the card. After importing to the computer, you can either chosoe to convert to DNG or not. The advantage of converting to DNG would be the support for embedded metadata - IPTC info and so forth - rather than requiring XMP sidecar files or whatever other scheme your image management software might employ to record information about your files. But you have to consider whether it's worth the extra time it takes to convert and/or the possibility that some information might be lsot in the translation (even though it isn't *supposed* to be). And some people have very strong feelings about which format is more likely to be readbale 20 years from now. Me, I don't pretend to know the future.
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