85L and "chopped bokeh"

Check the photos below to see what I mean by "chopped". Both with 85L@1.2 on a 5D2.
Only PP applied is saturation and contrast boost so that this problem is more evident.
You can clearly see some bright bokeh ellipses (mostly orange) chopped vertically.

At first, I found the chopped bokeh a bit weird but unique and I liked it.
But now I find it more and more annoying, especially on the second example photo where the bokeh gets very distracting.

Reading around, it seems that this problem is caused by the mirror box clipping the lens cone at large apertures... so the 85L is not the culprit, it's just a 5D2 "bug"

What do you think about it ?
Does this happen also on 1Ds bodies ?

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That is interesting. I notice from shot #1 the more central oof highlights look symmetrical, only the edge ones are asymmetric.

I think you might need to try some controlled testing. You could try a large piece of cardboard with lots of small holes popped in it. In a dark room put a bright light behind.

Position the camera so the various holes cover the various positions in the frame covering edge to edge both horizontally and vertically.


Photograph it with various degrees of oof and at different apertures.

Yes, a function of the camera at large apertures. Can happen with many lenses.

Hmm this would be frustrating...

Ive seen something similar on photos with my 40D and my 85 f1.8, but caused by something different, such as shooting at a large aperture but having something such as a leaf or wire mesh blocking part of the image in the foreground. It cuts the bokeh down one side in a similar way.

Interested to know if others have experienced as CheshireCat have with their 5Ds or 5DmkIIs.

That's normal performance for the 85L, don't worry about it.

I dislike it :/... Is it really on every camera? I watches many 85L photos on this forum and they seemed not to have this problem.

Well, that sucks.

A sticky aperture blade, maybe ?

I've noticed it on an XTi, 5D, 5D2 and assumed it was the same on all bodies.

That's the edge of the sensor box cutting off the bokeh...pretty much going to happen on any SLR. It gets more pronounced as the OOF highlights approach the edge of the frame.

This is normal for the 85L. It is often contingent on how OOF the OOF highlight is, with really OOF highlights being affected the most

Stopping down helps alleviate this

Here's a quick and dirty comparison I did between the 85L and the 35L. The 85L Is less contrasty and less saturated than the 35L wide open which makes it better for portraits but worse for landscapes (than the 35L)

35L:

I have to admit that on the pic above 85L doesn't look so good... :/

Do the contacts on the 85L cover part of the rear element, like they do on the 50/1.0? Because that looks very much like that "clipped" bokeh that was shown in a 50/1.0 thread recently, and it was explained that it's caused by the contacts.

Looking at images online, some make it look like they do cover part of the rear element, others don't. I rented one once, but I don't remember which is the case.

Brett wrote in post #8513724
Do the contacts on the 85L cover part of the rear element, like they do on the 50/1.0? Because that looks very much like that "clipped" bokeh that was shown in a 50/1.0 thread recently, and it was explained that it's caused by the contacts.

Looking at images online, some make it look like they do cover part of the rear element, others don't. I rented one once, but I don't remember which is the case.

Yes, the contacts do cover part of the rear element, and that may contribute to some bokeh clipping. However, the major culprit is the physical edge of the sensor/mirror box on the camera.

Easy solution - do not have lights in the background.

At least on the nifty fifty they are all uniformly pentagonal!