On Sharpness, ISO and Shutter Speed

Started Nov 29, 2013 | Discussions thread
Jack Hogan
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Re: On Sharpness, ISO and Shutter Speed
In reply to Bernard Delley, 11 months ago

Bernard Delley wrote: If I understand correctly you analyze the studio scene raw files downloaded from dpreview.

Correct

I am well aquinted with fvbergh 's excellent MTF mapper, as I used it to investigate focus shift (not posted so far).

Most excellent indeed

did you plainly apply the MTF mapper to the full raw and then select a useable slanted edge? Which edge is it actually ?

I feed MTFMapper the two slanted edges separately (labeled Horizontal and Vertical in the graphs), in the form of TIFFs cropped from the grayscale full resolution image obtained by clipping to zero and white balancing the relative Raw data. The data thus obtained is undemosaiced and as raw as it gets - you can read a bit more about my procedure here . Keep in mind that it only works with neutral subjects lit by a well behaved illuminant (such as D50)

What did you find out with your tests?

Jack

Vertical and Horizontal results are virtually the same on D4's DPR captures.  MTFMapper's results' accuracy decreases with increasing noise (see here )

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