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on Mar 9, 2017 4:16:27 GMT
Last Edit: Mar 9, 2017 4:48:02 GMT by mumucat
I'd appreciate some opinion of what's going on with the rear inside element on this lens. It's not cleanable as it appears to be inside the lens. I'm not sure if it's fungus or balsam separation, and more specifically what should I do about it? It's a beautiful lens otherwise. set: imgur.com/a/9GM1E~Mu |
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Status: Long, long time Contax and Yashica user; glad to be here and hope to contribute.
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on Mar 9, 2017 21:32:46 GMT
Last Edit: Mar 9, 2017 21:33:08 GMT by biggles3
Hello mumucat and welcome to the Forum, though admittedly in sad circumstance.
Without closer examination of the lens, it looks like you have a problem with the cement that bonds two elements together. On the Yashinon DX (and Super Yashinon DX) 135 f2.8 lens, the rear element is actually a group of 2 bonded elements and the marks in your photos suggest that the air has got into the space where the cement is and is causing the bond to fail.
If that is the case, it's pretty terminal I'm afraid. It is possible to remove, clean and re-cement them but the cost is astronomic and there are very few companies that can perform this service; it will be infinitely less costly to buy another copy of the lens.
I'm sorry I can't be the bringer of better news. Perhaps someone else on this Forum may have a different view or suggestion for a remedy... |
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on Mar 10, 2017 1:15:02 GMT
Last Edit: Mar 10, 2017 2:17:44 GMT by mumucat
Without closer examination of the lens, it looks like you have a problem with the cement that bonds two elements together. On the Yashinon DX (and Super Yashinon DX) 135 f2.8 lens, the rear element is actually a group of 2 bonded elements and the marks in your photos suggest that the air has got into the space where the cement is and is causing the bond to fail.
Thanks for your response. That's sort of the conclusion I came too as well as it doesn't seem to exhibit the sort of organic "branchy" structure of fungus I'm seeing in examples. That said, what sort of artifacts would I look for in photos? My understanding is that defects on the rear element affect image quality much more than the front lens. Will it continue to deteriorate quickly, or is it a slow process? I have a DX 50mm f/1.4 matching (silver and black) and would like to collect the series eventually. I've attached a quick snap of a dusty guitar (jpg 80% to fit forum size limits). I'm not sure if that sort of defect would show in bokeh? (Also a macro shot of the rear element) ~Mu Attachments:
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on Mar 10, 2017 3:23:57 GMT
Posted: Mar 10, 2017 3:23:57 GMT
I'll concur that it's not fungus. But it could be something else other than separation. Maybe it's on the front surface of the bonded elements, caused by condensation from a previous cleaning that wasn't done correctly. But if it's between the elements, it is an odd sort of separation, as that usually shows up as either a ring, or a flare from the side.
PF
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on Mar 10, 2017 3:49:07 GMT
Posted: Mar 10, 2017 3:49:07 GMT
The macro shot is much more interesting; the large cluster at nearly six o'clock does not look like separation - it looks more like a mineralised deposit. Ridgeblue has posited that there may have been an attempt before you acquired the lens to clean it; are there any signs that the rear of the lens had been disassembled at some time?
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on Mar 10, 2017 4:03:42 GMT
Posted: Mar 10, 2017 4:03:42 GMT
No, I don't see any obvious signs it's been opened. I couldn't find any reference online on how to disassemble this lens. It has a built in hood, and I'm not sure if disassembly is similar to Takumar lenses? I need to get the lens outside and take some photos and understand the impact better. I'm not a pixel peeper ususally, but if it can be cleaned there's a part of me that would very much like it fixed.
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on Mar 17, 2017 22:20:57 GMT
Posted: Mar 17, 2017 22:20:57 GMT
Guitar pic looks allright to me.
Just use it and look for a replacement while enjoying this lens.
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