Whitewater11 Loc: Ellensburg, Washington

Thanks for bringing this question up. I was fairly disgusted that I had to use my older cameras to do studio photography.

Zooman 1

Set the ISO to auto. Focus, then turn to the ISO you want and take photo. I do this with the R6, but only change the ISO when it is needed.

mdougc Loc: Sarver, PA

I have the EOS R, and I am guessing the controls are similar.
Turn off exposure simulation when using flash. That should give you an ambient light view.

amfoto1 Loc: San Jose, Calif. USA

With studio strobes I would use fully manual exposure (incl. no Auto ISO, because that makes M an auto exposure mode too).

The reason is that studio strobes aren't controlled ETTL, so there's no means of doing correct auto exposure (AE) with them. Any form of AE will cause an incorrect exposure. The camera's metering system will set the AE according to the modeling lights (if they're on) and ambient light conditions, and then when the strobes fire the image will be hugely over-exposed.

The viewfinder is a separate issue, as noted (and solved by the original poster).

There may be other times you need to turn off Exposure Simulation. If wanted, you could turn on the histogram to still be able to check exposure by ambient light (but not when shooting with non-ETTL flash or strobes).