This is an update to the previous post.

The Canon R6 (and other R cameras in the range?) have an exposure issue when using manual lenses.
I found that using an adapter with the sensor pads on (so focus peaking can be enabled) caused the image taken to not match the exposure in viewfinder or the live screen.

I first thought that it was my settings – checked them, all fine.
Then I checked my set up in camera – manual aperture, manual shutter speed, auto ISO – all fine
Hmmm strange.

I noticed that with the same camera settings, my Chinon 50mm (adapter with sensor pads) exposed 4 stops above what I was seeing in live view/viewfinder. (I thought it was a quirk of the lens)
I noticed this with the Helios and the Zeiss 135mm, again with sensor pads on the adapter.
I turned the F stop up to it’s maximum (F1.4) on the R6.
This helped a bit, but still did not really match between the shot and what I was viewing.

However, my Olympus 28mm (which I’m using to learn zone focusing) had a plain adapter with no sensor pads on it (I figured that as I’m zone focusing I wouldn’t need the lens to communicate with the R6 for focus peaking).
The exposure matches exactly with the shot taken and what’s seen in live/viewfinder.

So I ran a test, I ordered another adapter for my Chinon 50mm, but this time without sensor pads on it.
As soon as I put it on and fired up the R6, the exposure was no longer 4 stops higher.

One thing I did notice, he maximum F-stop the R6 goes to (in manual mode, with sensor pads on the adapter) is F1.4 – yet with the non sensor pad adapters fitted, this displays automatically as F00
The Chinon lens I thought I had a quirk, does not have a quirk at all, when fitted with an adapter that has no sensor pads on it, the exposure matches exactly between view and shot taken.

Why does this matter?
Is this a fault?
Why does the F-stop not go to F00 with adapters with sensors on them?
(This would allow the R6 focus peaking system to be used and the shots would be exposed identically to the view being shown.)

It was impossible to compose a shot when you had to reduce exposure by four stops to have the shot exposed correctly, due to being too dark in the viewfinder/live view.

I cannot afford to shell out anything like the prices asked, for even used glass.
I have to use adapted vintage glass or prime lenses would be off limits to me.
Besides which, it helps me to learn about aspects of photography and film, better than any book can.

If you want focus peaking on the R6 with vintage lenses, then pick up an adapter with sensors on it.
If you want your vintage lenses to expose the same for both your shot and what’s shown in the viewfinder/live view on the R6, then buy a plain adapter without sensor pads on it.

Be well.