Canon 1ds mkiii ISO settings

[Keith_Fitz]

I just came across this on Keith Coopers site, it makes interesting reading
http://www.northlight-images.co.uk/article...1ds3_noise.html

[Josh-H]

I just came across this on Keith Coopers site, it makes interesting reading
http://www.northlight-images.co.uk/article...1ds3_noise.html
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I did my own tests with my 1DS MKIII after reading that a month or so ago - I concur with the findings and switched off incremental ISO stops.

I mean if I need to go up in ISO from say 200 it really is much easier to go straight to 400 or 800 than to pissfart around in between - not to mention the noise benefits.

[Keith_Fitz]

It seems strange to have a feature which is counter productive, and how many shooters realize this? Another lesson learned.

[John Sheehy]

It seems strange to have a feature which is counter productive, and how many shooters realize this? Another lesson learned.
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Well, think of the context of a "good" photo - shadows well lit.  You won't see a difference if you don't have significantly deep shadows, because the extra noise that ISO 160 has over 200 on the 1D* series and the 5D is only read noise; a noise that isn't particularly visible in the highlights and midtones, especially at low ISOs.  If you expose to the right and only have a scene DR of say, 4 stops, you're not going to see the problems with 160; it will be slightly cleaner (1/6 stop less shot noise) than 200 in the midtones and highlights.

Of course, if you can use the same Av and Tv values at ISO 200 without blowing the highlights, you will get much less shadow (read) noise than at 160.

[daethon]

I just came across this on Keith Coopers site, it makes interesting reading
http://www.northlight-images.co.uk/article...1ds3_noise.html
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So...is this also the case with the 40D?  I can't seem to find confirmation as to whether or not the incremental ISO's are software driven, like with the cameras in this article, or if they are hardware impolemented

[Panopeeper]

So...is this also the case with the 40D?

The 1/3 stop ISOs and 3200 are numerical derivatives of the "real" ISOs.

Following layered TIFF contains the *raw* histograms (this is not, what the raw processors show) with ISO 100, 125, 160 and 200, in layers. The first histogram of a pair shows the entire numerical range, the second one is "zoomed in", reflects only the first 512 levels, one level in one column. The gaps and ragged tops indicate, that the values have been created wither by multiplication of smaller values, or by division of larger values.

Histogram layers