ISO on the R5

Quarkcharmed wrote:

bclaff wrote:

Quarkcharmed 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

How do we establish that? I don't see it in rawdigger. With the interim ISO values (e.g. 125, 160, 320, 500 etc.) there are no regular gaps in the histogram.

4ex:

There are strange regular 'dips' though but they present at any ISO setting including 100, 200, 400

Anyway digital amplification should have produced much more frequent regular gaps with bins at zero.

It not so obvious as with older Canon bodies but you can see the pattern in the Read Noise

I added the red lines to show how every whole ISO setting is the bottom of a group of three that have a straight line. The pattern is most obvious at low ISO settings.

Right, that's very interesting. It's prominent before ISO 1600 although a bit debatable after 1600. But maybe it's just the small scale that hides it.

However the question is, why doesn't it show in the raw histogram? Say if ISO 500 is ISO 400 digitally multiplied by 5/4, we should see clear gaps every 5th bar.

I suspect some mild filtering or dithering which hides the gaps you might expect to see.