M645 shutter timing

[farlymac]

Today while I was testing out my camera after putting in a new set of seals and bumpers I noticed that the seconds section of the shutter dial were mostly running long. 1 second was fine, but 2 was more like 3, 4 was 6, and 8 was almost 12. I have a theory about this, and it involves what type of battery is being used, so I was wondering if others of you M645 users have experienced the same thing, and if you've fixed it just by changing the battery either to a fresh alkaline, or by using a silver oxide version.

PF

 

[OlivierAOP]

I have a 1000s with a fresh alkaline battery. I have a shutter speed tester and 1/250 to 8s are spot on or within 0.1EV. 1/500 and 1/1000 are ~0.3EV too slow.

 

[nikon_sam]

If I recall I had a body that ran just like yours but if I placed the PD Prism on it the shutter speeds were correct...the prism uses the same battery that's in the body and has it's own shutter speed dial that over rides the body's shutter speed dial...I don't recall ever fixing it or if I still have that body...

 

[farlymac]

If I recall I had a body that ran just like yours but if I placed the PD Prism on it the shutter speeds were correct...the prism uses the same battery that's in the body and has it's own shutter speed dial that over rides the body's shutter speed dial...I don't recall ever fixing it or if I still have that body...

That works for me. Just tested it and got the same results as you did. Thanks for the input. My thought now is the shutter circuit of the camera needs tweaking, and since I don't have the test gear or manuals to do so, I'll just let it be and only use the slow speeds with the PD prism. I'm glad now I made that a priority purchase.

PF

 

[farlymac]

Here is a link to a post on PhotoNet about adjusting the shutter speeds on the M645 body. Most important part is to adjust it at the 1/60 sec setting, then all the other speeds fall in place.
https://www.photo.net/discuss/threads/adjusting-shutter-speeds-on-a-mamiya-645-body.438229/

PF