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Gyurmi
Tinkerer
Username: Gyurmi
Post Number: 12
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 12, 2010 - 06:41 am: | 
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I think everyone at this forum has been through the unhappy encounter with the sticky gunk found in the mirror housing and the back of old SLRs and also in some MF roll film holders. Here is another, less likely place, where the damn thing spreads its venom. (Mostly, this will be of interest to Canon collectors.)
http://members.ozemail.com.au/~gpauka/foto/Restoration/DeadlyFoam/index.html
Do you use foam in your restoration work? If so what sort?
(I'm more and more inclined to substitute it with fabric - wool yarn or felt. Earlier I bought some foam from Micro-Tools, but now I'm steering away from that, too. Not only because of the price...) |
Mndean
Tinkerer
Username: Mndean
Post Number: 232
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 12, 2010 - 02:22 pm: |
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That one's actually pretty well known around here. It's not the only brand with the problem, but seems to be the most affected. |
Paul_ron
Tinkerer
Username: Paul_ron
Post Number: 218
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 13, 2010 - 07:19 am: |
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The Olumpus OM1s have the same foam problems over the prisms. Shame they didn't have the forsight to see the future. |
John_s
Tinkerer
Username: John_s
Post Number: 18
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 20, 2010 - 10:22 am: |
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I found a similar problem with an old Canon FP, the foam eats away the silvering on either side of the pentaprism. If you clean it off down to the bare glass you can improve matters a little - thanks to total internal reflection?
It's easy to complain about them using foam, but these cameras are 50 years old - I guess the makers couldn't have known the foam would do this, and would have been surprised if they knew we would still be using them after half a century. It's amazing they still work at all, and often replacing the foam is not a difficult job.
Would you use a car with 50 year old tyres? |
Gyurmi
Tinkerer
Username: Gyurmi
Post Number: 15
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 22, 2010 - 06:00 am: |
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That 'fix' is an interesting proposition. I must admit, I didn't dare to clean it off thinking that it would make matters worse. But, once you do that, could you perhaps use some silver paint and black paint over it? Did anyone try? |
John_s
Tinkerer
Username: John_s
Post Number: 19
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 22, 2010 - 02:49 pm: |
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I tried putting silver foil over the patches, but it made no difference. Silver paint might be better. I think these pentaprisms rely on total internal reflection to reflect the light, the silvering just improves things slightly. When the silvering is removed, the plain glass still reflects the light but the edges can be seen. |
