Why 'more or less stopped using ISO'?

Started Feb 19, 2014 | Questions thread
D Cox Forum Pro • Posts: 21,845
Re: Why 'more or less stopped using ISO'?

bobn2 wrote:

The whole concept of 'ISO' is based around a methodology which says 'choose a processing regime' and then 'choose an exposure to match'. The implication is that the purpose of controlling exposure is to control output image brightness. If you are one who controls the processing after capture, for instance by processing from raw, then you don't want to control exposure to conrol brightness, you need to control it in order to capture the maximum scene information, then you process to get the required brightness. Since ISO is all about mapping from exposure to output image brightness, it isn't much use when you want to maximise capture information - then you need to use other methodologies for exposure control, which have become loosely wrapped up as 'ETTR' or 'ISOless'.

In any case, what you're trying to do is use all of the sensor's capture range for whatever is the luminosity range of the subject.

The problem I see with ETTR is the very small and low resolution display of the histogram on an LCD screen. Even in Photoshop's Levels control, it is poor (they haven't updated the display since screens were all 640x480).

This makes it difficult to find the highlights.

A "zebra" display might help (I haven't tried one), but would it show clipping on small specular highlights ?

(By the way, why do you write "methodologies" when you mean "methods" ? )

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