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01-19-2016, 01:48 AM   #16

Join Date: Dec 2010
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the 645D is optimum iso of 200. 100 is a compromise. dulls the highlights a bit.

01-19-2016, 10:38 AM   #17
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QuoteOriginally posted by Ed Hurst Quote
Thanks Thomas - that's the data I was referring to. It certainly seems to suggest that 100 is closer to base ISO than 200, otherwise it would lead to a reduction rather than an increase in DR.[COLOR="Silver"]
That being the case, then I do not know why ISO 100 would be in the expanded ISO when all other camera manufacturers have their base ISO available without making it available in a menu.
I am not saying you are incorrect, and the DxO data suggests that ISO 100 is the real base ISO, I am suggesting that this was a misstep by Pentax.
01-19-2016, 11:06 PM   #18

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cali92rs - I can only explain it with reference to the point above - that the firmware on the camera was closely based on that created for other bodies which may, perhaps, have had a base ISO of 200.

My experience is that overall DR and noise are optimised on the 645D by shooting at 100, not 200, but I cannot prove that scientifically so YMMV.

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