85 1.2 Clipped Bokeh

[Shane1.4]

I just bought an 85 1.2. Can anyone explain to me why the bokeh is clipped off on sides of the discs? My 135L doesn't do that.

From what I have read online it sounds like it is related to the mirror box. But then why don't my other lenses do that? Not sure I like the shape of the bokeh...

 

[Random Orbits]

A couple comments. The more elliptical shape of the light blurs as you out from the image center is due to the cats eye effect. The light that enters the center of the lens sees a circular aperture, but those that come in at more oblique angle will see a narrowed aperture (cats eye). Stopping down will reduce this effect. The truncated circles or cats eye are due to the shape of the light source. They are partially blocked by parts of the tree. Try taking a defocused picture of a single circular light source (i.e. single Christmas tree light from the top) -- it will be circular.

 

[Pinchers of Peril]

I had this exact same question when I first bought this lens. Check out this link, it explains everything http://toothwalker.org/optics/bokeh.html Basically the aperture for the 85 1.2 (aka the "Canon ball") is so freaking big that the light that it lets in gets partially blocked by the mirror box. I think the effect is worse on a full frame cameras and stepping down decreases it as well. You will see this effect mostly when shooting wide open. It is not, as others have stated, due to the light being blocked by something before it enters the lens (i.e. part of the tree) but instead the light is being blocked after entering the lens itself.

 

[BozillaNZ]

Yes, it's caused by the mirror box geometry blocking light rays exiting the rear element (essentially forming a rectangle aperture). Just something you have to live with by getting a f1.2 lens on an SLR type camera.

You can reduce the effect by stopping down, and moving the background lights further away the subject.

 

[alliumnsk]

would be interesting to compare this lens on a Sony A7