Last weekend I was shooting in studio and tethering to laptop as well.
First I measured everything and shot the portrait with a
24-70mm lens at
Then I switched to
85mm lens and didn't change anything and made sure I am still at
f/2.8 and shot the same thing.
But on laptop screen I noticed the light on the background seemed to be increased! But I didn't change anything, I just changed lenses.
So that made me think does the length of the lens affect the exposure even in these short lenses? When I do Large Format photography the length of bellows affects the exposure but hadn't seen such a thing for digital.