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Curiousart
Tinkerer
Username: Curiousart
Post Number: 1
Registered: 08-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 21, 2010 - 12:00 pm: | 
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Hi Folks,
I'm in the process of my first complete camera teardown and rebuild. The victim is a nice Ciro-flex Model C TLR.
As I was cleaning the viewing lens, I noticed a big, honking thumbprint on the back lens. Closer inspection revealed that it was on the *inside* of the lens! Dan Mitchell's thorough instructions state that the lens can be dismantled using a furniture cup on the inside rings. The rings on my lens are pretty solidly stuck on. My questions are:
1. Is a big thumbprint likely to even show up on the ground glass screen (I didn't notice it before, and the image on the screen was surprisingly bright and clear), and is it really worth the time to crack this thing open?
2. If I decide it is worth the time to bother to clean it, does anyone have any suggestions as to how to approach the job?
Thanks...
Art |
Glenn
Tinkerer
Username: Glenn
Post Number: 830
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 22, 2010 - 04:22 am: |
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As this is on the viewing lens it will do no harm to the image on the film and not hinder the process of composing the view you wish to record. On the other hand I am not saying that this insignificant thumb print will not become an ever increasing source of annoyance as you admire your first triumph - this all depends on one's make up and I am speaking from experience here!
If the old dodge of running a few drops of naphtha into the ring threads does not produce results then, if possible, I drill a couple of 1mm holes in rings that are normally hidden. Drilled diametrically opposite each other this will allow a pin wrench to be used and as the holes are so unobtrusive, the method can also be used on rings that are fully visible. If the drill bit used is new or has only been used to drill brass you will find that a small collet pin vice, rotated in the fingers, will easily produce the holes - just make sure that the bit is pushed well into the collet so only about 1/8"/3mm protrudes.
Most small electric drill are too bulky for deep drilling in lens barrels and do not give enough control over drill speeds - I use the above method for probably 90% of cases where repairs require drilling for re-tapping etc. |
Curiousart
Tinkerer
Username: Curiousart
Post Number: 2
Registered: 08-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 22, 2010 - 08:07 am: |
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Thanks for the great tip, Glenn...I wouldn't have thought of that. And yes, I'm afraid I also have the perfectionist gene that would allow a thumbprint to take the shine off of my fine accomplishment. It's probably a good excercise anyway, best tried on a nearly worthless camera(to other folks, at least), and on a part that's not integral to the actual taking of the photo.
I think I'll spend a little time searching for a furniture cup that fits the ring more closely, and if that fails, I'll start drilling.
Couple of questions:
-Will lighter fluid harm a lens or lens coating in any way? It seems unlikely that some of it won't get on the lens if I try to soak the rings.
-When preparing to drill, I'd imagine it'd be necessary to centerpunch a dimple into the chosen spot on the ring, in order to keep the drill from wandering. And in my case, where the ring is tapered at a steep angle toward the lens, this seems especially true. What's the safe way to go about this (assuming it's necessary)?
Thanks again! |
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