ISOless sensors, read noise and photography - many questions!

Started Oct 3, 2013 | Discussions thread
bobn2 Forum Pro • Posts: 59,657
Re: ISOless sensors, read noise and photography - many questions!

Steen Bay wrote:

bobn2 wrote:

Steen Bay wrote:

bobn2 wrote:

I think personal tests to one's own requirements are always the best - part of getting to know your camera. Just to add, the same goes for you raw processing tools.

The subthread below seems to confirm that. It seems that the ISO on the NEX 5N (and maybe other Sony cameras?) just is a tag in the RAW file. No gain/amplification or digital scaling/multiplication at all. Seems that DxO missed that!

The Sony raw coding is unusual, because they use a non-linear 12 bit code (at least in some cameras) - I think we'd want to look closely to convince ourselves that the non-linearity remains the same from ISO to ISO.

Edit: AsIliah's post confirms

The 'spikes' in (especially) the shadows (to the left) get wider as the ISO increases, but maybe that has something to do with long exposure NR? (suppose that "2, f/2.8" means 2 seconds, f/2.8)

I wouldn't expect NR to change the histogram on that scale, it would mean hugely visible smudging if that was true. Think, the nature of NR is to change pixels to very nearly the same tone, but within the same distribution of tomes that already exist. If it goes inventing new tones, the results will look very strange indeed.

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