XH2 - ETTR or employ the ISO invariance and ETTL?

Started 8 months ago | Discussions thread
Canadianguy Senior Member • Posts: 2,951
Re: They would both be shot at base ISO - there shouldn't be that much difference

Ollie 2 wrote:

ETTR (expose to the right) is a common method of using a cameras dynamic range to lift the shadows in camera and drop back the over exposed elements by reducing highlights in post production.


However given that cameras such as the new Fuji , series have enormous native ISO abilities is it now considered more prudent to ETTL and raise shadows in post much as they might have been in camera by using the ETTR method?

It seems from articles on ISO Invariance that Ive read that this might be the case.

Then again, I found those same articles utterly baffling.

Perhaps someone with a greater understanding of these things might point me in a direction - left or right. I mainly shoot astro or day to night Timelapse's.

ETTR is used when one wants to extract all the DR possible from a sensor. So it is shot at base ISO for the widest DR. The whole theory is based on there is more tonal information in the brightest areas of the raw file than the darkest areas - before clipping in a raw file.

The example given in the original article was a theoretic camera with 5 stops of DR recording to a 12 bit raw file (4096 levels available)

"Within the first F/Stop, which contains the Brightest Tones 2048 levels available

Within the second F/Stop, which contains Bright Tones 1024 levels available

Within the third F/Stop, which contains the Mid-Tones 512 levels available

Within the fourth F/Stop, which contains Dark Tones 256 levels available

Within the fifth F/Stop, which contains the Darkest Tones 128 levels available"

The math worked out that half of the tonal value information was contained within the (first stop of DR from the brightest area) brightest tonal area. There is just more information for one to play with when post processing a raw file to darken it than it was to brighten an image with 3% of the data from the darkest part of the raw file (last stop of DR from the darkness ares).

Hence, the advice to expose to the right at base ISO.

ISO invariance also has one shooting at base ISO - so why would you ETTL and raise the shadows if the ISO is the same - unless you need a shutter speed or aperture value to capture a particular subject.

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