Coating issue on rear cell?

[Daniel.E]

Hi!
I'm thinking of buying a lens that has something going on but I don't know exactly what it could be. It looks like coating but I thought I'd ask here first.

Thanks!

[djdister]

It looks more like cement/air separation between lens elements that are supposed to be cemented together.

[Daniel.E]

Thanks! That would be a problem only under certain shooting situations, right?

[Kevin Crisp]

A problem only when you are shooting film and want a good quality image. It isn't confined to an edge, it is in the middle too.

I was tempted to say pass on that one, but it depends what the lens is and how hard it would be to reglue. If the problem is not obviously right on the surface of the outermost glass of the rear element, it is likely separation which is an expensive problem to fix.

[Daniel.E]

It's a 24cm Heliar. It's obvious if you look at it under the right angle/light. Pass?

[ic-racer]

If you want a huge, sharp, silver-based conventional negative, I'd pass on that. Might work great for other processes if the price is right.

[Daniel.E]

If you want a huge, sharp, silver-based conventional negative, I'd pass on that. Might work great for other processes if the price is right.

Yeah, that's what I want right now. Thank you for the input, I'll pass then.

[Kevin Crisp]

Some people have suggested that separation can be cured by letting oil wick into the gap. Not a good solution. But this one kind of looks like I'd think that would look.

There are lots of great sharp lenses available in the 240 focal length. 240 G Claron for one.

[Steven Tribe]

There is no makeshift solution for this separation as the patches wil remain opaque. My guess this Is a post ww2 product with synthetic glue.

It can be fixed through hobby work! And you can use UV bonding synthetic glue or the original Voigtlander solution of Canada balsam. Neither is difficult. But the purchasing cost should be reduced.

Heliars are worth the effort!

[EdSawyer]

It looks like coating, not separation to me. that would not affect images much. Is there any rainbowing ? that would indicate separation.

[Daniel.E]

Yes I think it's coating too now, the seller told me it's on the outside of the rear cell.

[Kevin Crisp]

I didn't get an answer to whether it is on the surface. Coating issues, usually from faulty cleaning, generally don't have so much emphasis on the edges.

I'm not sure somebody starting out in LF really needs to get into recementing lenses right away....

[Daniel.E]

If the problem is not obviously right on the surface of the outermost glass of the rear element, it is likely separation which is an expensive problem to fix.

Sorry Kevin, I missed that one. Yes, the problem is right on the surface of the outermost glass of the rear element. That's what the seller told me.

It sounds tempting but I certainly wouldn't go into recementing lenses.

[Daniel.E]

Here's a video of what it looks like https://www.dropbox.com/s/qp2lx82fk0c5sby/video-1452561877.mp4?dl=0

[Kevin Crisp]

Interesting. If somebody slopped a little oil on the inside of the rear element, and then cleaned it off, you might get this effect. Some older coatings were very soft on vulnerable.

[Dan Fromm]

Why do you think the lens is coated? What is its serial number?

[Daniel.E]

The serial number is 3,xxx,xxx according to what I read after the 2,7xx,xxx the lenses appear to be factory coated.

[EdSawyer]

That's actually the inside of the rear cell, but indeed looks like coating issue as mentioned.