antonio_piu Posted May 18, 2022 Share Posted May 18, 2022 Two of my lenses (one from my GS-1 system and on from my ETRSi system) show some issues in the glass, I'm providing a couple of pictures below. The PG 50mm shows something that looks like little dots or droplets, it would look like condensation, but it certainly isn't. The PE 100mm has a circular smudge, like an abrasion or discoloration. Both issues are only visible under direct light, and if I'm not looking straight into the lens, but rather tilting them on a side. What do you think those are? In particular, I wonder if the abrasion on the external circle of the PE 100mm might have consequences in the final image. Any help or advice is highly appreciated. Thank you. Link to comment Share on other sites More sharing options...
conrad_hoffman Posted May 18, 2022 Share Posted May 18, 2022 I'm guessing that could be the beginnings of fungus (spots) and separation (edge). 1 Link to comment Share on other sites More sharing options...
antonio_piu Posted May 18, 2022 Author Share Posted May 18, 2022 I'm guessing that could be the beginnings of fungus (spots) and separation (edge). Thanks Conrad – I've only shot the one with potential separation as an adapted lens on my Canon 6D, so I have no way to judge whether it affects the image when used on my ETRSi. Do you think the beginning of separation on that peripheral point is likely to affect the final image on the 645 format? Link to comment Share on other sites More sharing options...
John Seaman Posted May 18, 2022 Share Posted May 18, 2022 I've shot with a number of lenses with edge balsam separation and I've never noticed any problem with the pictures. Lenses have to be pretty bad before image quality is affected. 2 Link to comment Share on other sites More sharing options...
m42dave Posted May 18, 2022 Share Posted May 18, 2022 I used to have an old Miranda 35mm screw-mount lens with some edge separation in the rear element group, and it did not visibly affect images. I have another lens with small bubbles in between two elements (similar to what your photo shows), and likewise it isn't an issue. If it was severe separation (e.g., due to impact) then it would be more of a concern. Link to comment Share on other sites More sharing options...
antonio_piu Posted May 18, 2022 Author Share Posted May 18, 2022 Thanks John, that's nice to hear. I have another lens with small bubbles in between two elements (similar to what your photo shows), and likewise it isn't an issue. So, you think that also is a separation problem? Because that's another lens, it's not the same that shows the clearly defined arc shaped defect. These are two different lenses. I should have done a better job when posting. But here is a quick remark: first two pictures are about Zenzanon PG 50mm (shows pattern like droplets) - last two pictures are a Zenzanon PE 100mm (shows a discolored arc). Link to comment Share on other sites More sharing options...
m42dave Posted May 18, 2022 Share Posted May 18, 2022 So, you think that also is a separation problem? It's hard to say from your photos, but it could be. Here is a photo of my lens with the little droplet-like bubbles, which I believe is due to separation. Enough spots or slight edge separation (like haze) could reduce contrast slightly due to light scattering, but I don't think it's anything to be concerned about. 1 Link to comment Share on other sites More sharing options...
JDMvW Posted May 18, 2022 Share Posted May 18, 2022 I'm with the school that sees Piu's problems as possibly the first stages of fungal growth. What's showing, in any case, is unlikely to have any serious effect on mage quality until it gets a lot worse. If it is fungus, and if it can be killed by UV or some such, not to worry. Link to comment Share on other sites More sharing options...
conrad_hoffman Posted May 19, 2022 Share Posted May 19, 2022 Definitely blast it with UV light, bright sun or whatever, for several hours. You don't want it to get worse! Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted May 20, 2022 Share Posted May 20, 2022 The first shot appears to show fungus contamination, and the 3rd and 4th are almost certainly the beginning of cement separation. Fungus, in its early stages, can usually be fairly easily cleaned away after dismantling, but cement separation generally can't be economically cured. However, as John says, the separation has to be pretty bad before it shows in the image. I have a 180mm Rodenstock (infamous for separation issues) Siranon LF lens that has separation across about 1/3rd of the lens surface - and it's still the sharpest lens I have for 5x4! There's a pretty rainbow patterning to look at as well. :rolleyes: Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now