Originally posted by jamesm007 The K-x does use RAW NR starting at ISO3200 as the K-7 this NR is twice as strong as used on the K20D at ISO3200 and probably much stronger than the K-7. This of course does not answer why your ISO1600 pic from the K-7 came out the winner. Try the test at ISO3200 and see what happens. The K-x does measure high DR but its also using much stronger NR.
Is this a comment directed at me?
What ISO1600 pic do you mean?
Where do you know the K-x raw NR from?
My test reveals the exact magnitude (of raw NR at ISO 3200 and higher, for K-x and K-7). Are there other sources for it?
However, I wouldn't say the K-x NR is stronger than K-7. Because of a flatter SNR slope, noise at ISO 1600 and 3200 turn out to be about the same, for K-x, where K-7 has stronger noise at 3200 than at 1600. But this is due to the steeper curve, not the stronger NR. The raw NR gains about 2.5 dB, the same for both cameras.
This gain doesn't seem to apply to the dynamic range though. Because shadows at low ISO are left alone.
Originally posted by georgweb I can only imagine how much work this was
It's like a mountain climb. Once you bite, you must continue to the summit. My respect for DxO has increased, actually
Originally posted by georgweb understand you are doing this with tungsten light and shutter speeds down to 1/15 or 1/10. This would comply with my needs (stage and social stuff without flash) and I just want to ask you whether your high ISO testing includes those settings and is therefore represented adequately in your charts.
I did the test as published at 2900°K tungsten, f/4.5 and 1/15s for ISO 100. I decreased shutter for higher ISO. Just today I retested. One variation was to keep shutter at 1/15 and decrease aperture down to f/22. Both SNR curves lie on top of each other. So, I could confirm that short shutter speeds below 1/10s don't differ in noise (I explained in my blog why this is to be expected). So yes, my results should apply to your shooting style.
Originally posted by jamesm007 The trick is the RAW converter its needs to be a neutral
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GBG also writes his own raw converters he has some serious sensor knowledge.
Yes, GBG deserves our respect. BTW, he did write a RAW file reader but no raw converter. He can manipulate dot data but not create an RGB linear image. He didn't do the demosaicing which is the hard part.
A raw converter cannot be neutral. A raw converter creates 3N color channels from N raw channels. This implies creating cross-correlation between neighboring color channels. By varying amount, I do agree. But never zero. It isn't possible mathematically. At 1/4 the resolution, yes. But not at full resolution.
This is why inspecting the standard deviation of rwa dots BEFORE any raw conversion is interesting. I didn't do this though. DxO may do exactly this, don't know though. But interestingly, they don't measure chroma noise ...