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Geowelch
Tinkerer
Username: Geowelch
Post Number: 22
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 17, 2009 - 05:59 pm: | 
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I've been searching all over for information on how to calibrate the rangefinder on a Mamiya Press 23. This is the early body type. I've found some postings on Photo.net on how to calibrate the later models, such as Super 23 and Universal, but the viewfinder/rangefinder on the early models is quite different. A friend's camera is badly out of whack and I volunteered to try to fix it. Since I also have one it would be good to know how to do this.
I got the top off, as well as the plate covering the rangefinder assembly. The screw above the mirror apparently adjusts the vertical alignment but I can't figure out how to adjusts for distance (horizontal movement). The mirror doesn't move at all during focus, but there is a sliding lens assembly between the mirror and the viewfinder which does, so it must have something to do with that. I'm told that is how Leica rangefinders work. If any of you have any information on this I'd really appreciate if you could pass it on, or point me to a reliable source. |
Bossman
Tinkerer
Username: Bossman
Post Number: 6
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 17, 2009 - 06:14 pm: |
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I have only seen one or two of those in my over 40 years of camera repair but I have a hunch the rangefinder adj'mt is perhaps inside the film chamber or somewhere outside the top housing. Let me knowif that helps! Art www.flcamerarepair.com |
Geowelch
Tinkerer
Username: Geowelch
Post Number: 23
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 17, 2009 - 08:45 pm: |
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Thanks Art. I wonder if it has something to do with the little spring-loaded activation lever that presses against the back of the lens helix. |
Bossman
Tinkerer
Username: Bossman
Post Number: 7
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 17, 2009 - 09:11 pm: |
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The adj'mt will probably be a small screw or set screw behind a cover screw. Some cameras have the range adj. screw access hole under the accessory shoe cover. |
Geowelch
Tinkerer
Username: Geowelch
Post Number: 24
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 18, 2009 - 10:08 am: |
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Bossman, the only cover screw is just above the adjustment for vertical alignment. I don't see anything for horizontal alignment. |
Markus
Tinkerer
Username: Markus
Post Number: 99
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 18, 2009 - 08:54 pm: |
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Perhaps the horizontal adjustment works like for Feds and Zorkis, where one needs to adjust the arm that is pushed in by the lens as it is focused.
I just checked on my Standard 23, and this arm is actually held in place by a screw that is covered in some kind of yellow varnish. You can see it when you remove the lens. The arm that transmits the focus position of the lens is the one that has the shiny metal pin attached to it. It looks like it would be a pain to adjust. You'd need a very stubby screwdriver to loosen the screw. For my 90mm lens, when at the infinity setting it pushes this lever all the way in, and I mean all the way to the limit where it cannot move any further. So you can achieve the same effect without a lens by pushing the lever all the way in by hand.
Good luck - Markus |
Markus
Tinkerer
Username: Markus
Post Number: 100
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 18, 2009 - 09:34 pm: |
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Please disregard my previous post, I just took the top off my Standard 23, and figured out how to adjust the rangefinder... boy, what a weird mechanism.
With the top cover off, look at the front (like if you were looking right at the lens), to the right of the large rangefinder window (see the photo)
There is a metal plate, roughly 1/2 inch squared that swings back and forth (and also a bit left to right) when the lens is focused. There are four set screws in that metal plate that need to be adjusted (on my camera these are covered in varnish, which looks darker in than the rest of the plate in the photo). Apparently, the one to the right in the image above is for the adjustment at infinity, the one on the left for the adjustment at the closest focus distance, and the others are for adjusting the focus at two in between distances (it looks like it might be at 15 and 5 feet distances). There is a long set screw (you can see its hole in the camera housing in the picture just underneath the metal plate) that limits the forward movement of the metal plate. It has nothing to do with the adjustment of the rangefinder. |
Geowelch
Tinkerer
Username: Geowelch
Post Number: 25
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 18, 2009 - 09:54 pm: |
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Now that is really bizarre! But now that you point it out, I can see how it would work as it fine-tunes the degree of movement of the viewfinder lens. Thanks Markus! If you don't mind I'd like to post your solution to Photo.net as I posted the same question in the medium format forum there. |
Markus
Tinkerer
Username: Markus
Post Number: 101
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 18, 2009 - 10:09 pm: |
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Sure, no problem, go ahead and post it there. |
