should I send it back?

Just got a schneider g claron 210 f9 for 50 bucks. The seller said it has a little dust, but both pair of cemented elements are separating. I kind of want to repair it using some new basalm. I don't know where to get basalm and if it's worth the risk. Anyone have any experience re cementing lenses? Any suggestions?

And fyi its the plasmat model

Hmm. On the one hand, $50 is a good price. On the other, taking the lens apart, soaking the separated groups in the proper solvent, probably MEK, receenting and resassembling isn't a small job. If you want to play, play. Me, I'd send it back and wait for a better one to turn up.

I take it the lens is in barrel. If you're willing to use a slightly faster dagor type in barrel, keep an eye out for a 210/6.8 Boyer Beryl. They're good lenses, the cells are direct fits in a #1 (usually, my 210/7.7 Beryl S's cells aren't) and $50 might get you one.

but both pair of cemented elements are separating.

Unusual in a Schneider lens, much more common with Rodenstocks.

Are you sure you're not confusing a simple loss of edge paint with cement separation? Cement separation looks like a rainbow oily patch across a portion of the lens - usually moon-shaped - and spreading toward the centre of the lens. Whereas loss of edge paint shows as bright speckles or a bright circle only at the very edge of the lens.

I think lens makers stopped using Canada balsam many, many years ago, and separating doublets is a difficult job these days.

OTOH, touching up a loss of edge blackening is extremely easy using a black permanent marker pen.

Me, I'd send it back and wait for a better one to turn up.

+1 to that, if it is indeed cement separation.

Perhaps a picture or two might confirm the diagnosis.

It's not exactly clear from those pictures, but it looks like misting from fungus that's been cleaned away.

I have an enlarging lens in similar condition. A light misting that can only be seen in a bright light will reduce contrast very slightly, but resolution should still be good.

The difference from a perfect sample will be similar to about midway between an uncoated lens and a coated one.

It also looks like the edge blackening is less than perfect, but that's par for the course with old Schneiders.

Unusual in a Schneider lens, much more common with Rodenstocks.

 

Are you sure you're not confusing a simple loss of edge paint with cement separation? Cement separation looks like a rainbow oily patch across a portion of the lens - usually moon-shaped - and spreading toward the centre of the lens. Whereas loss of edge paint shows as bright speckles or a bright circle only at the very edge of the lens.

 

I think lens makers stopped using Canada balsam many, many years ago, and separating doublets is a difficult job these days.

 

OTOH, touching up a loss of edge blackening is extremely easy using a black permanent marker pen.

 

+1 to that, if it is indeed cement separation.

 

Perhaps a picture or two might confirm the diagnosis.

Very old lenses might have separation from all manufacturers. But several decades ago the German government banned the glues used in those old lenses and all German lens manufacturers had to change the glue they used. Rodenstock had no more problems with separation then Schneider and lenses from Rodenstock after that change have not had that problem.

You may have unfortunately bought enough old lenses to have experienced problems with one or the other. But Rodenstock lenses do and did not have this problem for decades. Since I was the U.S. product manager from 86 till 2015 I have personal knowledge with this. And you have never handled as many a Rodenstock lenses as I have or talked to as many users and dealers as I have.

Lastly, process lenses are not normally used in a darkroom, enlarging lenses are. I operated a Robertson process camera in the AF and sold lenses to commercial print shops for process camera use. They were all outside the wet area.

Thanks for your response. I am not at all familiar with large format lenses. I believe they handle flaws much better than 35 mm lenses. Would you expect that seperation around the entire circumstance of the lens, say 1/4 of the way to the middle, would affect the IQ much?

Maybe not, but these things progress overtime and then could effect IQ. Why not just look for a better lens?

Very old lenses might have separation from all manufacturers. But several decades ago the German government banned the glues used in those old lenses and all German lens manufacturers had to change the glue they used. Rodenstock had no more problems with separation then Schneider and lenses from Rodenstock after that change have not had that problem.

You may have unfortunately bought enough old lenses to have experienced problems with one or the other. But Rodenstock lenses do and did not have this problem for decades. Since I was the U.S. product manager from 86 till 2015 I have personal knowledge with this. And you have never handled as many a Rodenstock lenses as I have or talked to as many users and dealers as I have.

Lastly, process lenses are not normally used in a darkroom, enlarging lenses are. I operated a Robertson process camera in the AF and sold lenses to commercial print shops for process camera use. They were all outside the wet area.

Thanks for your response. I am not at all familiar with large format lenses. I believe they handle flaws much better than 35 mm lenses. Would you expect that seperation around the entire circumstance of the lens, say 1/4 of the way to the middle, would affect the IQ much?