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Can someone explain how ISO/Base ISO functions these days? (alien.top)

submitted 11 months ago by Spirit-Subject@alien.top to c/photography@viewfinder.pro

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So generally, I’ve always understood that the lowest ISO is best to shoot at. Though with newer cameras, they usually have a higher base ISO and in some cases Dual ISO.

I usually work with the R5C, even for photography. It feels odd to take portraits at 800 ISO because I’ve always been told it should be as low as possible.

So does the Base ISO system, negate the need to shoot at lowest ISO for the clearest and least grainy image?

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[–] codenamecueball@alien.top 1 points 11 months ago (4 children)

The dual ISO is for video in order to capture maximum dynamic range when using LOG profiles. It’s got little to no relevance for stills photography, unless you’re shooting stills in log. Max DR for stills is usually at 100, with the R5 sensor it’s 50 according to our friends at DxO.

https://www.dxomark.com/canon-eos-r5-sensor-review-a-high-water-mark/

[–] spider-mario@alien.top 1 points 11 months ago (2 children)

Maximum DR ≠ minimum noise. The DR is higher at low ISO because the highlight headroom is higher, but the noise floor also is, and if you are light-limited, the latter may be more relevant.

[–] codenamecueball@alien.top 1 points 11 months ago (1 children)

Look at the other graphs. Best noise performance and colour depth is also at lower ISOs

[–] spider-mario@alien.top 1 points 11 months ago

“SNR 18%” is higher at lower ISO, but is also 18% of a higher saturation point, so it’s the SNR for a higher amount of light – no wonder it’s higher. For a fixed amount of light, as in low-light situations where you might be limited to, say, f/2 and 1/100s, the highest ISO setting that doesn’t clip anything you care about will lead to less noise. (More or less depending on the camera.)

See figure 6 of: https://www.mdpi.com/2079-9292/8/11/1284/htm

Or: https://www.dpreview.com/reviews/image-comparison/fullscreen?attr134_0=canon_eosr5&attr134_1=canon_eosr5&attr134_2=canon_eosr5&attr134_3=canon_eosr5&attr136_0=1&attr136_1=2&attr136_2=3&attr136_3=4&attr176_0=efc&attr176_1=efc&attr176_2=efc&attr176_3=efc&normalization=full&widget=487&x=0.06014373975539024&y=1.0840726817042607

(The effect is more extreme with the EOS RP.)

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