Rokkor 58, 1.2 - incorrect viewfinder focus

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HawkEyeMedia
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p.1 #1 · Rokkor 58, 1.2 - incorrect viewfinder focus

I have a question to all you manual focus lens experts.
I recently bought the wonderful Rokkor 58mm f1.2 lens for my Canon 5d2 and I noticed that it's really hard finding the focus through the viewfinder. I decided to point the camera towards a tape measure, using f1.2 and 0.6m distance. I found that the lens consistently focuses about 2 cm closer than visibly indicated in the viewfinder (Ee-S focus screen). It did several tests and I don't have an idea if there's anything that I can do about it.
I'm new to the MF world and would appreciate any leads on how to fix this.

Thanks

Dec 26, 2012 at 05:38 AM

LightShow
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p.1 #2 · Rokkor 58, 1.2 - incorrect viewfinder focus

Search for viewfinder shims/washers.
one I found on the subject:
http://www.fredmiranda.com/forum/topic/766050

Dec 26, 2012 at 06:08 AM

HawkEyeMedia
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p.1 #3 · Rokkor 58, 1.2 - incorrect viewfinder focus

Oh great. I didn't know. I'll see if I can order those somewhere...

Dec 26, 2012 at 06:29 AM

scottam10
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p.1 #4 · Rokkor 58, 1.2 - incorrect viewfinder focus

I had the same problem with mine; the position of the focus screen needs to be adjusted.

- when I first installed it, the defocus was obvious - I was using AF but it looked visibly OOF in the viewfinder - however the shot taken was sharp, so the AF had it right

Turns out the focus screen wasn't seated properly, I just took out the focus screen, and reinstalled it, and the problem was fixed. Washers/shims are an option if that doesn't work

Dec 26, 2012 at 07:39 AM

HawkEyeMedia
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p.1 #5 · Rokkor 58, 1.2 - incorrect viewfinder focus

I checked the focus screen and it seems to be installed correctly.
I then did a test with thin layers of tape and an old focus screen.
I think I need to move the screen up a tiny little bit...

Dec 26, 2012 at 08:40 AM

helimat
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p.1 #6 · Rokkor 58, 1.2 - incorrect viewfinder focus

The 5D2 uses the EG-S screen, rather than the EE-S. Can you confirm which you have, and if it is the wrong one, could that be causing the problem?

Dec 26, 2012 at 04:56 PM

HawkEyeMedia
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p.1 #7 · Rokkor 58, 1.2 - incorrect viewfinder focus

hm... interesting. I do have the Ee-s focussing screen. The problem persists when I use the original screen that came with the camera.

Dec 26, 2012 at 07:18 PM

helimat
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p.1 #8 · Rokkor 58, 1.2 - incorrect viewfinder focus

HawkEyeMedia wrote:
hm... interesting. I do have the Ee-s focussing screen. The problem persists when I use the original screen that came with the camera.

Could be shimming. Mind you, the accuracy with the original focus screen will be off at f/1.2 anyways, as it is incapable of providing that small of a depth of field.

Dec 28, 2012 at 01:10 AM

HawkEyeMedia
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p.1 #9 · Rokkor 58, 1.2 - incorrect viewfinder focus

I was able to remove two washers. Now the focus is off by under a Centimeter. Good enough for now.
Thanks for everybody's help.

Dec 28, 2012 at 02:44 PM

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