"Chopped off" bokeh with 50mm f/1.4 on 400D

Hello, does anyone else see parts of the bokeh get chopped off with their 50mm at f/1.4 when using a 1.6 crop body? I put mine on my 400D and took shots of some lights at maximum aperture. The following was taken at far-focus:

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Interesting theory. I hope the optics experts chime in here. On the surface, that sounds about right to me, but I'm no optics expert and couldn't definitively comment.

It appears to me there is somthing in front of the lens that is not in focus and we cannot see that is causing the cutting off of the light.

I will experiment with mine and see if I can repro the problem.

Interesting...do you have any other pics that do this?

It happens a lot on fast lenses with point-source OOF highlights. I dunno why, but have seen it from the 50's, 35 and 85.

I never noticed that...here is a 100% crop of the bokeh...

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Yes, it has to be an interaction between the lens and the cropped box. This was taken with the same lens at f/1.4 on a 35mm film camera:

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When you ordered this lens, did you use the name David or Don? It is the letter D you see in the highlights. Custom made for your initials. They hate it when William orders one.

The further that the OOF highlights are from the center of the lens, the less round they will be. It has to do with the shape of the aperture blades. It happens with any lens.

from Bob Atkins (http://www.bobatkins.c​om …aphy/technical/​bokeh.html)

Here is one that confirms the OPs thoughts (http://www.vanwalree.c​om/optics/bokeh.html)

It seems that the oblique (non-round) shape is caused by the lens, while the "chopping" is caused by the mirror box.

wow, interesting read. I never noticed that in my shots. great investigative work guys

Never to old to learn something new!
Thnx for that link!

bacchanal wrote in post #5167097
The further that the OOF highlights are from the center of the lens, the less round they will be. It has to do with the shape of the aperture blades. It happens with any lens.

from Bob Atkins (http://www.bobatkins.c​om …aphy/technical/​bokeh.html)

Here is one that confirms the OPs thoughts (http://www.vanwalree.c​om/optics/bokeh.html)

It seems that the oblique (non-round) shape is caused by the lens, while the "chopping" is caused by the mirror box.

The 50 1.4 and 85 L do it even on the 5D.