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Matt
Tinkerer
Username: Matt
Post Number: 4
Registered: 01-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 17, 2010 - 06:07 pm: | 
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Brought in my GSN to the repair shop to get the electronics working... when it came back, the yellow rangefinder patch is pretty much invisible now. The guy claims he didn't. Rather than argue with him, is this a correctible thing. Can I replace/repair the viewfinder. I have no way of focusing now.
Thanks. |
Tom_cheshire
Tinkerer
Username: Tom_cheshire
Post Number: 271
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 17, 2010 - 06:23 pm: |
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Sure. The "patch" is a piece of glass semi-silvered or semi-reflective depending on how you like to describe it. If it is totally invisible it may have fallen out when the camera was being fixed or it shifted out of place or out of the proper angle. If it is still in there, just put it back in place. If it is missing, replace it. If it was damaged by the repair guy attempting to clean it and, instead, "wiping" it clean, replace it. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 163
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 17, 2010 - 06:49 pm: |
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Or in that last case, have the repair shop make good on their screw-up. Why should you have to pay for it?
If you want to find this material to replace it yourself, Edmund Scientifics has it; look for 50% beamsplitters. |
Mikel
Tinkerer
Username: Mikel
Post Number: 205
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 17, 2010 - 06:51 pm: |
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Probably "wiped out" when he attempted to clean it.
The camera is probably older than he is. Nevertheless, many if not most of the RF cameras of the era can have the silvering "wiped" by someone who is attempting a cleaning and doesn't really understand what is going on. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 164
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 17, 2010 - 07:00 pm: |
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So how hard is it to get the top cover off just to check? If not too difficult, my suggestion would be to do so to see what the situation is exactly. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1061
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, February 17, 2010 - 07:40 pm: |
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Here's the beamsplitter link. This stock is silver, rather than gold, but it works well and it's durable.
http://scientificsonline.com/product.asp?pn=3043359 |
Matt
Tinkerer
Username: Matt
Post Number: 5
Registered: 01-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 18, 2010 - 12:07 pm: |
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Thanks, everyone. This is very helpful To be more specific, when I look through the viewfinder, there is no yellow patch where there used to be a clear one. BUT... but when I cover the viewfinder with my hand I can see the yellow patch clearly against the black... don't understand why.
Where exactly is the beamsplitter mounted? I assume if I order a new one, I'll have to cut it to size? Are there any good pictures of this process?
Forgive my ignorance, I'm new at this. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 166
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, February 18, 2010 - 12:50 pm: |
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The beamsplitter is mounted at a 45° angle in the path of the viewfinder, in front of the eyepiece. It combines the straight-through image through the viewfinder with the rangefinder image in the center. Yes, it must be cut to size, but that's fairly simple to do; the size isn't critical. Generally the beamsplitter will be cemented in, either on both sides or to an angled bracket inside the rangefinder.
When I cut one, I found that the best tool to use was a carbide or diamond scriber to scribe a fine line, after which you just break off the piece as you would with ordinary window glass, just on a much smaller scale. |
Georgeboosh
Tinkerer
Username: Georgeboosh
Post Number: 7
Registered: 04-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 19, 2010 - 08:11 am: |
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There is a good diagram showing how a rangefinder works and the position of the beamsplitter here:
http://photozone.de/slr-vs-rangefinder
Alternatively, a simpler and cheaper fix is to stick a small piece of black tape on the front viewfinder glass the same size as the yellow rangefinder patch would have been. Your test with the hand in front of the viewfinder shows there is a beamsplitter in place but the yellow tint has faded/been rubbed off. There is a link here:
http://rick_oleson.tripod.com/index-165.html |
Matt
Tinkerer
Username: Matt
Post Number: 6
Registered: 01-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, February 19, 2010 - 11:57 am: |
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Awesome. Thank you, everybody. George... that photozone diagram is great. Very helpful for someone (me) who is not familiar with the mechanics of a rangefinder. |
Matt
Tinkerer
Username: Matt
Post Number: 7
Registered: 01-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 04, 2010 - 11:05 am: |
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Okay... so, I took the top off the camera, and replaced the beamsplitter with one from Edmund Scientific (thank you for the link, Rick) Here's the problem: the framelines are reflected properly, but I'm still not getting any viewable rangefinder patch (the diamond). Any ideas as to what the problem could be?? Could something else be out of alignment?
I'm pretty sure I mounted the new glass correctly... after all, there is a groove for it and brackets (and looking at the old beamsplitter it's not actually in terrible shape... so that might not have been the problem in the first place, though it was fun to open up the camera).
Thanks in advance. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 196
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 04, 2010 - 11:34 am: |
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Well, it's such a simple system that there aren't too many possibilities why it doesn't work correctly. Either something is so far out of whack that the optical path through the rangefinder patch is waaaay out of alignment, or something's blocking that light path (though I would think that you would have seen that after opening up the camera).
Take another look at the rangefinder and let us know what you see. Try moving the focus from lock to lock and see if you can catch a glimpse of anything where the rangefinder patch should be in the viewfinder. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 197
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 04, 2010 - 01:00 pm: |
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Another possibility is that the silvering has come off of the moving mirror or prism that operates the rangefinder. (This is a mirror, not a beamsplitter.) Easy enough to check with the top off. |
Bernhard_prins
Tinkerer
Username: Bernhard_prins
Post Number: 23
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 04, 2010 - 01:16 pm: |
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Hallo Matt,
Maybe two things may be wrong now:
or the new beamsplitter is mounted the wrong way around or the mirror itself has come off when removing the cameratop...this has happened to one of my GS camera's too when lifting the camera top. |
