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ISO on the R5

Started 10 months ago | Discussions thread
Quarkcharmed
Quarkcharmed Senior Member • Posts: 2,713
Re: I see!

MarshallG wrote:

bclaff wrote:

MarshallG wrote:

Disclaimer: I’m only the messenger.

I’m at a trade show all weekly so I stopped in the Canon booth and spent a long time talking with one of their experts about the R5.

He then me that the R5 sensor slightly boosts voltage as you increase ISO,

Not slight but in proportion to the ISO setting.

and it did so in one stop increments.

True of many Canon bodies including the R5

Intermediate ISO changes are made post sensor read,

True of many Canon bodies including the R5

so he said that you can get a cleaner image at a higher ISO setting that falls on a full stop boundary, than on an ISO setting which is between 1/3 to 2/3 stop lower.

I strongly suspect that the effect on image quality is not noticeable.

So he is absolutely correct, except that it absolutely does not matter in any meaningful way. No point in changing our practices as a result of this.

With all due respect to Bill's analysis, there must be gaps in the raw histogram which I don't see, so potentially it's more complicated than just digital multiplication.

Say if you multiply ISO 400 values to get ISO 500, you have to multiply each value by 2^(1/3) = 1.256, basically 5/4.

With integer digital numbers there will be gaps each 5th value - it won't be contributing to the raw histogram and we'll see the regular gaps.

 Quarkcharmed's gear list:Quarkcharmed's gear list
Canon EOS R5 Canon EF 70-200mm F2.8L IS II USM Canon EF 24-70mm F2.8L II USM Canon EF 16-35mm F4L IS USM Canon EF 50mm F1.8 STM
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