Canon 50mm f1.2 focus problem

[Nick De Marco]

I have juust received a lovely condition of the Canon 50mm f1.2 screw mount rangefinder lens from ebay.
I have put it on my M8 with the M adaptor and it does not focus correctly at f1.2 (looks to me like it is focussing about 6 inchis nearer than the subject). I have not had the same problem with my Canon 50mm f1.4 on the M8 with adaptor.
Does anyone know what this problem is? Should I complain to the seller? Is this something I can resolve simply?
Thanks

 

[noimmunity]

I remember reading there was some discussion of examples of this lens needed collimation. While you're waiting for a real answer, try poking around to see if you can find the relevant thread(s).

 

[bmattock]

Possible that you have a reversed lens element? This lens commonly suffers from crud, and perhaps someone cleaned it out, but got the lens back together wrong.

Other thought might be that with the narrower focus band that 1.2 has at close distances, you are discovered a misalignment of your rangefinder that the DoF of other slower lenses 'hid' from you before.

I don't know, these are just guesses.

 

[Never Satisfied]

I have been using my 50mm f1.2 today on a borrowed M8 and I have to say that the focus is bang on. I've been using it for quite a while with my film bodies without issue. As per the previous post, perhaps it has a transposed element???

 

[Nick De Marco]

The focus looks OK at f4, so I am not sure if that could occur with a transposed element. But at f1.2 and even f1.4 it is not focussing propely

 

[georgef]

I found the 1.2 backfocusing on my RD1 as well. I did not want to adjust my body as it works well with my nokton 1.4, so I "off-focus" for the 1.2. Kind of a trial and error thing most of the time.