Bokeh seems "chopped" off

I was testing a 6D + 50L and noticed the top of the highlights were "chopped" (sometimes the bottom, depending on their location within the frame). I looked up elsewhere and read it's due to the mirror box cropping off the light path.


6D + 50L

Actually the Sony lens is cut-off too, look at the single highlight to the left of the frame. The Sony does better because the maximum aperture is 1/3 stop smaller.

The effect is caused by something blocking off the light path, but I think it might be the rear of the lens itself. Or it could be the mirror box. (edit - looking again closely I think it is both. The oval cutoff shape seen in both the Sony and Canon is probably due to the mount, and the flat cutoff shape seen in just the Canon is probably the mirror box.)

Very large apertures will tend to run into this when the size of the rear pupil is constrained by the size of the camera opening...the diameter of the lens mount or the mirror box.

Finally, a fast 85mm will be worse than a fast 50mm, because the aperture is going to be 70% larger for the same f/#.

That's expected, and that's the mirror box. Blame reflex cameras

The 50L/1.0 and 85L/1.2 do have EF mount contacts partially covering the light path from the last element, but the 50L/1.2 does not (if I remember correctly).

You can stop down a bit to avoid the issue, if it bothers you.
... or go mirrorless

CheshireCat wrote in post #18068648
You can stop down a bit to avoid the issue, if it bothers you.
... or go mirrorless

Seems like you'd have to shoot a lot of things with these kinds of highlights in the background to make a complete brand switch worthwhile. I poked around and the number of shots I've taken where such a thing is likely to show up was two. And in both, I happened to have stopped down a bit anyway.

Indeed. Not a showstopper for me either

Though I found it annoying in a few cases, with the 85L wide open:
https://photography-on-the.net …hread.php?t=742​412&page=1

This would drive me up the wall. Especially for being the opposite of a budget lens. Ugh.

Very best,