Canon LTM 50mm f1.2 lens calibration

nandemofoto

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Dec 29, 2008
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Location
Nagoya, Japan
Hello everyone,
Recently I purchased the Canon LTM 50mm f1.2 which turned out to have a haze in the inside element. The element was cleaned and re-cemented by FocalPoint. There is still something that looks like little splash of haze in it but according to FocalPoint it will not affect the image quality (I guess I will just have to take their word for it).
The problem I'm having however is with the lens focus. After reassembling it the focus seems to fall above the intended object.
I tired it with my ZI and R-D1 and the same problem occurred.
I reassembled the lens twice to make sure that all the elements are where they should be but it didn't fix the problem.

I am guessing the lens requires calibration but I'm not sure which ring or screw is responsible for it.

* I would appreciated if somebody pointed me in the right direction.*

The pictures were taken with R-D1 in a camera shop at f1.2 and f1.4
On the first one the intended focus point was word "FIRE" but seems to be on the box above it.
On the second one intended focus point was in the in the lower part but again is above it 😕




 
It is probably the shim, but could be a misaligned element.

If it is just the shim, you need a thicker one as the lens is focussing behind the RF.

Did you send the entire lens to Focalpoint, or just the glass group with the problem? I suspect if the lens was off, Focalpoint would have taken care of it. Taking it apart after getting it back would probably nullify that.

Since you have an RD-1, try to get a photo of something that indicates how far off the focus is. Then shoot something flat to indicate a problem with a corner.

I use the wood fence in the front yard.

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The test that I did with my Canon 50/1.2, made out of two parts lenses. I also used the Fence, but did not scan those.

After shimming.

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Brian,
Thank you for your response. I live in Japan and sending all lens to FocalPoint was kind of expensive, I only sent the inside element and reassembled the lens myself.
Unfortunately I don't have digital RF to do more tests the one I used was at the camera shop.
I remember the shim was kind of loose maybe I should use some kind of tape or glue to keep it steady...
 
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