ISO on the R5

Steve Balcombe wrote:

Quarkcharmed wrote:

MarshallG wrote:

Quarkcharmed 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, and it did so in one stop increments. Intermediate ISO changes are made post sensor read, 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.

Again, I’m just relaying what the man told me. Don’t flame me, I’m just reporting.

It's very easy to verify following this article

https://www.rawdigger.com/howtouse/iso-is-seldom-just-digital-gain

AFAIK it was true for some very old cameras but now most of the ISO range (except the 'extended' parts) is implemented through the variable analog gain.

Again, I’m only reporting what the representative from Canon told me (“You’re welcome”) and I have not looked at a bunch of bar charts to confirm his statement. I’m just telling you what he said.

Yes, I see it's a Canon rep's claim not yours, I'm just saying it's very easy to verify.

It depends what you call "very old". I remember learning that the 7D Mark II, and others of that generation, performed best at ISO 160 and 320, and maybe 640, and to avoid the 1/3 stops in between. Above that the noise tended to swamp any other difference. However with the R5 it's different - there's a clear peak in performance at ISO 400, so much so that it's rarely worth using anything less, unless there's enough light (or shutter time) to use base ISO.

I want just a single button to toggle between 100, 400 and auto. That's all I use. Saves me a dial for ISO adjustments.

But the claimed 'full stops' thing is not apparent.

As always, Bill Claff has the data!

https://www.photonstophotos.net/Charts/PDR.htm