# What chopped off my (Bokeh) balls?



## Pinchers of Peril (Dec 9, 2013)

Hey everybody so I was looking at a bunch of shots I've taken recently with my 85 1.2 II on my 5dIII. I've noticed that on a number of shots that are taken wide open, the bokeh balls seem to be "cutt off" on parts. I've attached a picture to show what I am talking about. If you look at the upper right hand part of the frame you can see some of the out of focus highlights appear as balls with parts that are "sliced off." I've heard some people say something about the light gets cut off by the mirror box or something like that, but I was just curious what you guys thought. I basically just want to verify that this is normal functioning for both the lens and the camera.


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## Eldar (Dec 9, 2013)

Do you have any issues with distortion or focus problems in the part where the bokeh is odd? To me it looks cut on the upper left and looks deformed top center. I have never noticed anything like that with mine, but I sure have to try it out.


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## Pinchers of Peril (Dec 9, 2013)

Yeah the upper left part of the frame is actually the arm of a couch that was in front of the christmas tree so that's why those are a little bit blocked. I haven't noticed any distortion or focus problems.


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## kennephoto (Dec 9, 2013)

Isn't it just the armrest of the couch in from of the lights blocking that part of the light from hitting the lens? And the rest are just reflections in the elements of lens or maybe a filter on the front of your lens creating the bike ball cutoff reflection on the other side of the photo.


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## Random Orbits (Dec 9, 2013)

Normal. I think the term used is optical vignetting. For fast lenses used wide open, the lens barrel blocks the rays from the periphery. Take your lens off and look through it head on. You'll see a circular aperture. Now tilt the front of the lens away from you and you'll see a "cat's eye" starting to take effect. If you stop down, the aperture is smaller and is a smaller ratio compared to the lens diameter and the effect is reduced. Stop down enough and all the balls will be circular.

The chopped off cats eyes are obstructions in front of the light sources that prevent them from being "circular."


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## trof2 (Dec 9, 2013)

Random Orbits said:


> Normal. I think the term used is optical vignetting. For fast lenses used wide open, the lens barrel blocks the rays from the periphery. Take your lens off and look through it head on. You'll see a circular aperture. Now tilt the front of the lens away from you and you'll see a "cat's eye" starting to take effect. If you stop down, the aperture is smaller and is a smaller ratio compared to the lens diameter and the effect is reduced. Stop down enough and all the balls will be circular.
> 
> The chopped off cats eyes are obstructions in front of the light sources that prevent them from being "circular."



Very true. Stopping down once makes the condition barely noticeable for me. Additionally, you can frame your shots to keep point lights away from the far sides of the frame, where the effect is most noticeable.


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## Pinchers of Peril (Dec 10, 2013)

Here is another example that is hopefully more clear (please excuse all the christmas tree shots). You can see the lights at the top of the christmas tree appear to have the bottom of the "cat eye" shape cut off and then the lights lower down appear have the tops of them cut off.


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## TM (Dec 10, 2013)

Nice pics. I own the same lens too.That's how the bokeh looks at f1.2 at certain distances. If you stop it down slightly, they will become slightly smaller and more circular.


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## Grumbaki (Dec 10, 2013)

I can vouch for it too, it's a common "feature"(as in "it's not a bug it's a feature") of off center bokeh balls when shooting wide open with the 85L. Generally not really handicaping the general picture but can be OCD'd on.


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## Rienzphotoz (Dec 10, 2013)

I like the title ... witty ;D


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## bornshooter (Dec 10, 2013)

Rienzphotoz said:


> I like the title ... witty ;D


+1 awesome title  the lens is awesome have not noticed that with mines yet will need to do more testing,do you use a filter in front of it?


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## East Wind Photography (Dec 10, 2013)

Yes this is normal wide open. You also get some other "features" using this lense wide open. It's better to use it stopped down to f2 or more when you can. However the plus is you can use it at f1.2 but you just need to be aware of the features it offers at that aperture.


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## Pinchers of Peril (Dec 10, 2013)

Thanks for the responses everybody. Good to hear that this is normal for the lens. I do use a filter on it, but it sounds like that should not be what's causing this. When I use this lens I usually use it wide open because I'm going for that "special 1.2 look." Also I feel like since I paid so much more for this compared to the 85 1.8, I feel obligated to shoot wider than 1.8 ha ha ha. Yeah, I hadn't really noticed this "feature" on the lens until recently (probably because of all the christmas lights up around my house) and now that my eye knows to look for it I can't help but see it. It doesn't really bother me, it's just one of those things you can't unsee once you know it's there.


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## johnhenry (Dec 10, 2013)

Bokeh from point sources depends on three things:

Shape of the diaphragm, the amount the point source is out of focus and the distance the bokeh is from the optical axis of the lens.

At or near the center, it should be spherical or nearly so, and will distort the further you are from the optical axis.

However, this effect should be consistent for all points at the same distance but will have different orientations.


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## Pinchers of Peril (Dec 10, 2013)

Here is an interesting article I found regarding this. http://toothwalker.org/optics/bokeh.html


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## mackguyver (Dec 10, 2013)

Pinchers of Peril said:


> Here is an interesting article I found regarding this. http://toothwalker.org/optics/bokeh.html


Cool find!


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## Rienzphotoz (Dec 11, 2013)

mackguyver said:


> Pinchers of Peril said:
> 
> 
> > Here is an interesting article I found regarding this. http://toothwalker.org/optics/bokeh.html
> ...


+1


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## Click (Dec 11, 2013)

+2 Thanks for sharing.


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