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Krafty5260
Tinkerer
Username: Krafty5260
Post Number: 10
Registered: 02-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 07, 2008 - 09:25 pm: | 
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Okay, I get some crazy ideas when I have too much time on my hands. I've had a cold all week, so I've had time to think about cameras more than usual.
Does it make any sense that an otherwise nice lens with a damaged front element could have that piece of glass reproduced by an eyeglass optical company using the orginal as a pattern?
Am I nuts?
Now, don't just say yes; that's the easy way out. If I am, why? The other glass elements should still be okay, they're deeper inside the barrel. Hey, I've had stranger ideas than this one.
thanks,
Michael |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 531
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 07, 2008 - 10:26 pm: |
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I won't say you're nuts, but no, It makes no sense at all. The eyeglass company will probably not have the correct type of optical glass (there are lots of different kinds, and there are at least 2 different kinds in any camera lens). They will also probably not be prepared to match the curvature of the camera lens element, as even the most extreme eyeglass prescription is a much flatter curve than almost any camera lens element. The curvature of a camera lens element also has to be absolutely perfectly centered on the piece, a problem that eyeglass makers don't have to deal with, and the piece has to be cut to exactly the right diameter so that it will fit in the barrel without stress but with no clearance that would allow it to sit off center within the mount. Even on the odd chance that they have the correct glass (which is nil) and can grind it to shape (which is about the same), there remains the question of coating the lens. Here you're in luck, at least antireflective coating does exist in eyeglass lenses, and they can probably do that part.
Unless the glass is matched and ground perfectly, you will have a lousy lens when it's all done... and it will have cost you a BUNDLE. Unless this is an extraordinarily rare lens that will remain extremely valuable even with a nonoriginal element and functionally unusable performance, you will spend many times more on this unsuccessful attempt than the cost of simply replacing the lens.
Even replacing an element with one from another identical lens is something that I would only do as a last resort, because I don't have an optical bench to analyze the performance of the result. |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 281
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 03:55 am: |
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I have swapped lens elements between "identical" lenses just to see if that was possible. Rick is right, at least in a majoity of cases, it is NOT. The lenses I had apart (zooms, poor cases of heavy abuse, that is to say they were lost anyway) only LOOKED identical, inside they were considerably different. I first thought the differences were cosmetic alterations or design gimmicks which they were not, so in just two cases (out of ten) lens swapping brought the desired result. |
Krafty5260
Tinkerer
Username: Krafty5260
Post Number: 11
Registered: 02-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 06:40 am: |
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Hey Rick,
That is a terrific answer. Now, I have a little better idea of what goes into lens design. It's not just the bottoms of soda bottles stuck together. I knew I could count on this group to set me straight.
thanks again,
Michael |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 533
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 06:44 am: |
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There are some low budget hacks that you can do, and if it can be done cheap I've probably done it. Some of them are fun and educational, but they are not a recipe for excellent optical performance. |
Pablomartinez
Tinkerer
Username: Pablomartinez
Post Number: 92
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 01:26 pm: |
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I brought one Yashica A from Japan with an upper lens that was slightly scratched. I asked to an optical company that usually works with military stuff how much will cost to have a custom made lens for the yashica and the answer was around the thousand euro for a coated lens. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 535
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 08, 2008 - 02:23 pm: |
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A company that does military work may not be the low price leader.... still, I think you would be very unlikely to find a better price than that for a custom made lens. In fact, for a one-off that sounds like a bargain. |
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