Mamiya Press—trouble seeing image when focussing

[Ohio Sean]

Hi folks,

sorry if this has been asked before, but I’ve done a lot of searching and can’t seem to find a pre-existing post. I recently purchased a Mamiya press super 23 body and I’m having trouble focusing. as many will know, this is a rangefinder camera and has a split image in the viewfinder. As you turn the focus ring on the lens the two images are supposed to merge into one when you have achieved focus. The problem I’m having a hard time articulating is that the images that are to be focused into one are incredibly difficult to see. It’s a faint yellow circle in the center of the viewfinder and while I can use this when there is an incredible amount of light, anything less than full sun makes seeing the images well enough to use them as a focusing aid nearly a gamble. I just never feel certain I have reached full focus.

Has anyone else ever had an experience like this, or does this sound like an obvious issue to anyone?I’ve thought about taking the rangefinder apart and cleaning it, but I can see through the rangefinder just fine. Yes, there is a small amount of dust, but nothing that I can imagine would cause this issue. Not understanding how the rangefinder works well enough to consider what likely issues could be is a handicap. Maybe there’s a mirror or something inside that is incredibly dirty and therefore diminishing its appearance in the rangefinder. I just don’t know!

Any help at all would be very appreciated. I’ve been all over the Internet and have found several sets of directions for adjusting range finders and syncing them with lenses, but I don’t think that’s my problem. I just developed a roll of film shot this evening and it looks like I was able to achieve focus but it took an incredibly long time for each shot, could only be done with large amount of light, and I was never sure I had achieved focus. Not a single time. Very frustrating!

Thanks!

 

[shutterfinger]

1. download the service manual https://learncamerarepair.com/downloads/pdf/Mamiya-Press-Super23-Service.pdf
2. you need a new beamsplitter mirror listed as half transparent mirror.
Beamsplitter mirrors reflect a percentage of the light hitting them and transmits the rest. A half transparent is a 50/50 beamsplitter. They are getting harder to find and you'll likely have to cut a larger piece to fit in the camera's rangefinder.

 

[gordrob]

Have a look at these sites. They may be able to lend some assistance to your quest.

https://www.photo.net/discuss/threads/mamiya-super-23-rf-adjustment.486273/
https://www.photo.net/discuss/threads/calibrating-range-finder-in-mamiya-press-universal.12328/
https://tinkeringwithcameras.blogspot.com/2015/03/mamiya-press-restoration.html

If you run into problems with your Super 23 parts wise let me know. I have a collection of parts for these cameras and may be able to help. A lot of the parts I have are for the film backs but also some body and lens parts parts.
The download link that shutterfinger posted is a good start for parts numbers and identification.

Good Luck
Gord

 

[shutterfinger]

I'll give you a brief primer on rangefinder operation. The beamsplitter/transparent mirror is in line with the viewing eyepiece and is at a 45° angle to the eyepiece and the view window on the front of the camera. A few inches away is a movable mirror also at a 45° angle at infinity with a window in front of it. The image that passes through the transparent mirror and the one reflected by the movable mirror are superimposed on one another when the lens is in focus or the target distance is focused on. The movable mirror is camed so that its movement corresponds to the focus characteristics of the lens. Some cameras such as Linhof or Graflex use user replaceable cams while others have the cam type linkage built into the lens that couples with the camera body. I suspect that the Mamiya Press lens has the cam linkage in the lens.
The movable mirror may reflect through other windows internal of the body as well as other mirrors.
A replacement transparent mirror must be installed with the coated side facing the front of the camera. Newer transparent mirrors are thinner their predecessors and have to be shimmed so that their front surface is at the same position the original was.
Newer transparent mirrors do not have the tint that their predecessors had.

I might consider repairing it for you if you are uncomfortable attempting it yourself.

 

[halfaman]

At least 50 mm f/6.3, 75 mm f/5.6 and 100 f/2.8 lenses have a cam, I know it because I sent the whole equiment for rangefinder adjustment (very painful process) and it is what the technician told me. I read in some forum (maybe here) that 100 mm f/3.5 has no cam.

 

[Daire Quinlan]

At least 50 mm f/6.3, 75 mm f/5.6 and 100 f/2.8 lenses have a cam, I know it because I sent the whole equiment for rangefinder adjustment (very painful process) and it is what the technician told me. I read in some forum (maybe here) that 100 mm f/3.5 has no cam.

Yes, from some service manual I read, you were meant to adjust the RF so that it matched the 100mm F/3.5, then adjust the ring at the back of the other lenses to match the rangefinder. It's not a cam as such, it's that brass ring at the back of the lens that hits the RF post, it's adjustable in the other lenses, not in the 100 f/3.5

 

[Ohio Sean]

Hi, Folks,

Based on the article (which ironically I'd seen a few days ago) suggested by Gordrob:
https://tinkeringwithcameras.blogspot.com/2015/03/mamiya-press-restoration.html
I'd say there is a very good chance my RF is simply in need of a good cleaning. Unfortunately the process sounds incredibly daunting! Screws are one thing, but prying apart pieces fastened with glue and removing the leatherette sounds like a nightmare. It's the kind of thing that might take a Saturday, or might wind up with me sending a box of "parts" to a repairman and keeping me from using the camera for months and costing more than I paid for the body. Bummer!

Gordrob--you mentioned having parts--especially for backs. I'm definitely interested in a 6X6 mask for the K back. You wouldn't have one or know of a source, would you? I'm thinking about taking measurements and seeing if I can come up with something using a laser cutter, but I don't fully understand how they were mounted to the back or even the material they were made of. I'm assuming it was something similar to what dark-slides are made of.

Shutterfinger--thank you so much for the breakdown and link to the manual! You mentioned possibly doing this if I didn't feel comfortable with it. Are you a repairman? Do you do things like this on occasion?

Daire Quinlan--one of the links submitted by gordrob was a question you submitted in a different photo forum depicting troubles you've experienced with getting the RF focus re-calibrated. I'm curious--were you able to get this straitened out finally and, if so, what was the solution?

Sean

 

[shutterfinger]

I'd say there is a very good chance my RF is simply in need of a good cleaning.

Transparent mirrors of that vintage coating fades out or rubs off with even the lightest cleaning.
I'm a self taught camera repair technician. I'm a retried electronic/ mechanical technician. Reading that this camera's rangefinder is calibrated with a specific lens I'll pass unless you have that lens.

 

[Ohio Sean]

Actually it's the only lens I have. The 100mm 3.5 is considered the standard lens for the camera so that's the one I ordered / started with. And I agree--how to clean these mirrors? Are they similar to mirrors in an SLR that crumble when touched?

 

[shutterfinger]

The see through silvering either fades (dye based?) or separates from the base glass then comes off when touched.
The mirrors used in the day were .060 inch thick and current ones are .037 inch thick. The other mirrors are rear coated so they will not scratch with gentle cleaning.

The last beamsplitter I purchased came is small sheets and has to be cut to the size needed for the camera rangefinder. Patrice your glass cutting skills.

 

[mark fewtrell]

anyone the correct size for beamsplitter on mamiya universal?

 

[ags2mikon]

Or cut a small piece of colored gel filter and tape over one of the rangefinder windows.

 

[mark fewtrell]

2x 31x 51 mm