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01-29-2009, 01:59 PM   #1
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The heartbreak of... element separation

I took a chance on a broken Pentax-M 40mm f2.8 pancake. I fixed the focus problem by straigtening the focus ring, adjusting infinity and tightening the screws. I replaced the lost tiny bearing that makes the aperture ring click - 1.5mm fits great, BTW. I was able to disassemble the rear elements without any drama. But I couldn't fix this:



Oh well, it's probably not too bad in the center.

01-29-2009, 02:15 PM   #2
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Well, post-just-one-picture-more-Dave, which you made with this one. I'm curious what will come out of it.....
01-29-2009, 02:46 PM   #3
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QuoteOriginally posted by Just1MoreDave Quote
Oh well, it's probably not too bad in the center.
you can send that lens to me, i will scientifically inspect how this defect affects IQ on both APS-C and FF, and some form of measurebations.
01-29-2009, 06:39 PM   #4
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Early into my shooting with a K1000 I had a M 100 f/4 macro, with which pictures never came out right - cloudy, little contrast, a lot of flare. Eventually I realized it had element seperation. With a hood and away from a light source, it did pretty well, but I eventually sold it on eBay (with full disclosure!) after getting a Tamron 90mm. Of course that lens is pretty sweet to begin with ... not sure how this M40 will fair.

01-29-2009, 06:50 PM   #5
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Send it to Jsherman999, he'll get great pictures out of it. He got a picture accepted to PPG and it was taken with a cardboard tube from a roll of toilet paper that had a magnifying glass glued to it.
01-29-2009, 07:10 PM   #6
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Quick question: Is it possible to repair the lens when the elements begin to separate? I have an old Soligor 28mm 2.8 M42 mount that's showing that exact same thing behind the front element, and I'd like to get it fixed...
01-29-2009, 07:33 PM   #7
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QuoteOriginally posted by Damn Brit Quote
Send it to Jsherman999, he'll get great pictures out of it. He got a picture accepted to PPG and it was taken with a cardboard tube from a roll of toilet paper that had a magnifying glass glued to it.
now im curious, what picture is that?
01-29-2009, 09:19 PM   #8
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QuoteOriginally posted by VF-19 Quote
Quick question: Is it possible to repair the lens when the elements begin to separate? I have an old Soligor 28mm 2.8 M42 mount that's showing that exact same thing behind the front element, and I'd like to get it fixed...
It should be possible. Some solvent to get the elements apart, cleaning, then recementing. How hard can it be? Of course the cement needs to be something that won't alter the optical properties of the lens. The lens coatings need to be intact. It needs to end up with no air bubbles and be a consistent thickness. The lenses need to maintain their alignment. It's like a lot of lens repairs - either you pay someone a lot of money or wing it yourself.

01-29-2009, 09:27 PM   #9
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My local camera repair place wouldn't do it. They said chuck it, or use it how it is. I think it would be very hard or very expensive to repair.
01-29-2009, 09:46 PM   #10
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On How It's Made they showed how the elements are glued together using a special glue that doesn't distort. Pretty interesting how it's done.
01-29-2009, 09:50 PM   #11
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QuoteOriginally posted by graphicgr8s Quote
On How It's Made they showed how the elements are glued together using a special glue that doesn't distort. Pretty interesting how it's done.
Oh yea... i remember that... and how it's massaged in and all that.... so much care is put into it..
01-29-2009, 11:13 PM   #12
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Maybe you can try to remove the back group and put the lens in a bucket of water which you warm up very slowly (as in a couple of hours), gradually reaching the boiling point of water. This can make the glue soft again; maybe it will melt enough to get rid of the problem.

But only do this at your own risk of course
01-30-2009, 08:38 AM   #13
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Just keep it and wait, eventually somebody will be selling the same lens with nicked front element and good back element on FLEEBAY, so you can make one good lens out of 2.
01-30-2009, 09:42 AM   #14
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Lens repair is within the realm of DIY. I know how many that have used the UV cured products like listed here.
Summers Optical: Optical Cements, Structural Adhesives, and Cementing Supplies for Military and Commercial Applications
01-30-2009, 11:06 AM   #15
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QuoteOriginally posted by Rense Quote
Well, post-just-one-picture-more-Dave, which you made with this one. I'm curious what will come out of it.....
OK, here's one. I think this was f5.6, at the minimum focus distance.

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