Possible focus error on Mamiya M645 Super.

[tkamiya]

I'm not 100% sure I have this problem and am continuing to test but I'd like to hear ideas and opinions from fellow Mamiya M645 Super owners.

I have an M645 Super and 150mm f/3.5 lens. If I focus on a flat plane from let's say 10 feet away and exactly so that two halves of the split prism image line up, they don't seem to focus exactly.

This is only apparent on very small aparture such as f/3.5 where depth of field is very narrow. Also, on infinity focus, the focus ring goes all the way to dead lock and the prism image does line up, but the micro prism area is not clear.

Is there anything that can wear out, deteriorate, or drift in the camera that can cause this focus shift/error?

 

[keithwms]

Insulting question, perhaps, but is the ground glass mounted correctly? It should be with the frosted side toward the mirror. Did you recently put in a new screen or something? Any other recent changes? Do you get anything similar with another lens? (I"d say try with a really fast lens...)

 

[tkamiya]

Keith,

I made sure the ground side is facing the mirror. Actually, it won't fit, because of a tab, if it wasn't. I seem to be OK with 80mm f/2.8 but the deapth of focus is wider with this lens becuase of the focus length. Could this be lens though? If that were the case, would I even be able to focus via view finder?

No, it's not insulting at all. I thought of it as well. Thank you.

 

[eeb0705]

I had a focus problem with my 645 super a few years ago. Pretty much the same description, only occurred at large apertures. It turned out that the mirror had a problem and was not in the proper position. The fix was to send it to Mamiya for repair.

 

[keithwms]

I had a focus problem with my 645 super a few years ago. Pretty much the same description, only occurred at large apertures. It turned out that the mirror had a problem and was not in the proper position. The fix was to send it to Mamiya for repair.

That being the case (if it the case), before spending money on repair, I would consider going to another body or hopping to the (I think superior) mamiya 645 pro line.

 

[tkamiya]

Keith,

Yeah, I know. The replacement cost of these bodies are so low, it simply isn't worth sending it in for any type of work. Last work that had to be done, I did it myself. (flash contact problem) I'm not sure to be sad about this or be glad about this....