Canon 50mm f1.4 SSC - with bubbles

[stu_jenkins]

Has anyone ever encountered a problem of bubbles around the edge of a lens element? It's not balsam separation because it isn't a group - it's a single solid element.

Here's my 50mm f1.4 SSC:

The bubbles are on the third element. Here it is on its own:

It probably wouldn't have any visible effects when using the lens on a camera, but it's unsightly and I'd like to fix it if I can.

If the bubbles are between the glass and the layer of black paint, would I have any success if I removed the paint, polished the edge of the element, and then repainted it? I would have to be very careful not to damage the optical surfaces - I can see from the purple reflections that it's coated on both sides. The rules out using any solvents to get the paint off, and I wouldn't be happy about using any kind of adhesive tape to protect the lens from scratches.

Maybe a layer of food-grade cling film on each side, with tape on top of that? Then I suppose I would have to gently sand away the paint until I could get a good surface to polish and repaint.

Thoughts, anyone?

 

[rick oleson]

It's the black edge paint separating from the glass. The separation starts with little white bubbles like you're seeing, after a long time it may begin flaking off. The effect is a very slight increase in flare from the new reflective surfaces, and the little flecks of black paint floating around inside your lens can get into places where you don't want them. I would ignore it until you see some signs of paint actually flaking off of the glass; at that point you can disassemble the lens, carefully remove any loose paint and repaint it with black enamel. Doesn't matter whether you use gloss or flat, as it's the paint/glass surface that does the work.

I would NOT polish the glass surface where the paint goes - you'll find it's frosted in that area, which is good both for avoiding reflections and for good paint adhesion. I also would not use sandpaper or solvents to remove the paint: when it's loose enough to be time to remove it, you should be able to mechanically flake it off pretty easily. Anything that sticks too hard, just leave it, it's still doing its job.

 

[stu_jenkins]

Sounds like good advice. Thanks Rick! 🙂

 

[Noserider]

I'm not totally certain but I think that might be a sealed group of two elements?

 

[farlymac]

Commonly referred to as "Schneideritis", after so many Schneider-Kreuznach lenses that have come down with it. I've never had an image quality issue with lenses like that, though it does make them hard to sell.

PF

 

[Mackinaw]

.......I've never had an image quality issue with lenses like that, though it does make them hard to sell.

Exactly. Image quality doesn't seem to suffer, but resale value. Whoa, big time hit.

Jim B.

 

[stu_jenkins]

I'm not totally certain but I think that might be a sealed group of two elements?

Elements 4 and 5 behind the aperture are glued together as a group, but element 3 is on its own. Picture from mir.com.my:

 

[Waus]

Richard Haw has an article on 'Schneideritis' on his great webisite:
https://richardhaw.com/

 

[zuikologist]

Interesting website, thanks for the link.

Richard Haw has an article on 'Schneideritis' on his great webisite:
https://richardhaw.com/