300mm Rodagon with Slight Edge Fungus

[sperdynamite]

I just acquired a 300/5.6 Rodagon enlarging lens for the forthcoming C252. It's very very clean save for 2 issues. A small but visible coating scratch on the front element and a slight amount of what looks like fungus at the extreme edge inside of the front cell.

On a taking lens I know this would never show up in an image. Is the same going to be true in this case? I am in a climate controlled environment so I also have to ask will the problem get worse?

I still have a chance to return it, but I don't believe I paid top dollar and also am thinking that a bird in the hand...

Anyway I'd love to know what the brain trust thinks about imperfect enlarging lenses.

[domaz]

I just acquired a 300/5.6 Rodagon enlarging lens for the forthcoming C252. It's very very clean save for 2 issues. A small but visible coating scratch on the front element and a slight amount of what looks like fungus at the extreme edge inside of the front cell.

On a taking lens I know this would never show up in an image. Is the same going to be true in this case? I am in a climate controlled environment so I also have to ask will the problem get worse?

I still have a chance to return it, but I don't believe I paid top dollar and also am thinking that a bird in the hand...

Anyway I'd love to know what the brain trust thinks about imperfect enlarging lenses.

Can you try cleaning the fungus? Or is it in between elements? If cleaned it should not get worse. The small coating scratch doesn't seem like an issue to me, enlarging or not I doubt you could tell the difference.

[sperdynamite]

Can you try cleaning the fungus? Or is it in between elements? If cleaned it should not get worse. The small coating scratch doesn't seem like an issue to me, enlarging or not I doubt you could tell the difference.

I do see a way to start disassembling the lens from the rear if I had a spanner wrench. Can't tell if the fungus is between cemented layers yet.

[ic-racer]

https://www.largeformatphotography.info/forum/showthread.php?160670-Can-this-lens-be-salvaged&p=1573241&viewfull=1#post1573241

Above is a link to a post showing some of the enlarging lenses I used on my Durst since 2008 . The glass looked pretty bad in the photographs, but the prints were fine. How do I know? On a whim a few years ago I insisted on getting new lenses. No change at all in my prints.

[Mark Sampson]

You won't be using the lens wide open, I imagine. So the fungus around the edge should have no visible effect. The scratch? In such a no-flare situation I think you'd never see any evidence of it.

[Erik Larsen]

I agree with the others that you’ll probably be fine. I use a 240 Rodagon that looks fine till you shine a light and look through it. Dust and scratches galore but I can’t tell any negative effects from them. I’m glad IC racer did his switch and didn’t notice a difference. It might bug some people to not have pristine glass but if the prints look good what more do you want.

[sperdynamite]

Thanks everyone, I think I'll hang on to it then. Ignorance is bliss sometimes! I'm sure it'll make beautiful prints once my C252 arrives.

[LabRat]

Could be worse... Read an article on PetaPixel yesterday about vids on TicTok on scratching lenses with rocks for effects... Some started with a clear filter, but some gal had to scratch front element with gravel...

Maybe a new trend??? :(

Steve K

[sperdynamite]

I got a spanner wrench and went at the rear retaining ring and man it would-not-budge! Any tips for loosening this thing? I'm pretty confident I can clean the fungus if I can get to it.

[paulbarden]

I got a spanner wrench and went at the rear retaining ring and man it would-not-budge! Any tips for loosening this thing? I'm pretty confident I can clean the fungus if I can get to it.

It is possible (likely?) that the retaining ring is lacquered in place (many time, this is the case), and so a couple drops of acetone would soften the lacquer and allow for removal of the ring. This would be my next move, if it were me.

By the way, you cannot grow fungus in the balsam layer, only on the air-spaced surfaces.

[domaz]

I got a spanner wrench and went at the rear retaining ring and man it would-not-budge! Any tips for loosening this thing? I'm pretty confident I can clean the fungus if I can get to it.

Acetone, as previously mentioned- also it always help to utilize a bench vise for situations like this. Either by using the vise to hold the lens (wrap it up in a rag so it doesn't scratch it) or by holding the spanner wrench. Either way you get a lot more levergae.

[Bob Salomon]

Acetone, as previously mentioned- also it always help to utilize a bench vise for situations like this. Either by using the vise to hold the lens (wrap it up in a rag so it doesn't scratch it) or by holding the spanner wrench. Either way you get a lot more levergae.

Assuming you get it apart, how would you assure proper centering and spacing when you put it back together?

[MartinP]

Acetone, as previously mentioned- also it always help to utilize a bench vise for situations like this. Either by using the vise to hold the lens (wrap it up in a rag so it doesn't scratch it) or by holding the spanner wrench. Either way you get a lot more levergae.

Also remembering not to use so much force, with the vice, that the housing of the lens is turned in to an oval and/or cracks an element. A couple of V-shaped bits of wood to spread the load around the lens periphery would be prudent. With the acetone, use a small amount, wait hours, use a drop more etc. etc.

[Conrad . Marvin]

Might be more dangerous for the lens to put it in a vise than to use it as is. If the pressure is enough to hold the lens without slipping, it also is probably making the lens somewhat oval and the retaining ring will be tighter than if it were round.

[FotoD]

Assuming you get it apart, how would you assure proper centering and spacing when you put it back together?

Using the same barrel and rings when you assemble it again?

I've had success with pipe clamps and a hammer with stubborn lenses. Just give it 1000 light taps instead of one hard blow, and make sure there are no set screws before you start.

I'd be careful with the solvents on a cemented lens.

[Bob Salomon]

Using the same barrel and rings when you assemble it again?

I've had success with pipe clamps and a hammer with stubborn lenses. Just give it 1000 light taps instead of one hard blow, and make sure there are no set screws before you start.

I'd be careful with the solvents on a cemented lens.
The requirements for spacing and alignment are much more demanding then simply replacing them.

[ic-racer]

Some of the shorter Compomom_S lenses can easily be reassembled with lens elements not fully seated (and not crooked either) and still with plenty of room to affix the retaining ring. Making it seem like reassembly was successful.