Mamiya C 55mm fungus removal

[David Lingham]

I’m looking for advise on cleaning fungus from a Mamiya C 55mm TLR lens. I can unscrew and remove the complete taking lens assembly easily. But I can’t undo the inner ring with the two notches that appears to give access to the lens element. Is this possible? Or best left to a professional. I’ve tried using a lens spanner, but it will not move. Would be grateful for any advise.

 

[jim10219]

It's probably best left to a professional.

Sometimes they are glued on. In which case you need to use a solvent to dissolve the glue. Choosing the wrong solvent can also dissolve the paint and make a huge mess, or have no effect on the glue. It could also just be jammed really tightly. That might require, heat, cold, a penetrating lubricant, or all of the above to knock it free. Do that wrong and you could ruin the lens or shutter. Also, when removing lenses, you have to make note of the orientation and spacing. If you put a lens in backwards or get the spacing wrong, your pictures will look terrible. And lastly, cleaning the actual fungus can be a pain. Do it wrong, and you can damage the lens elements, or not clean it all off, and the fungus will regrow pretty quickly.

Basically, there's a lot to go wrong here. So it might be best to let a professional handle it. Though there might be permanent damage to the lens already, in which case you'll pay a bunch of money only to get back a sub-par lens. That would likely be about half the price of buying another lens. So it might be worth giving the DIY repair approach a try, and if you do ruin it, just buy another lens. At least then, you'll get a known good one (hopefully), and some parts in case you need to repair the new one in the future. So yeah, there are no easy answers.

 

[David Lingham]

Jim, thank you for a prompt and comprehensive reply. Cosmetically the lens is good, and it wasn’t that expensive. The resulting negs are fine and overall I’m happy with it. Just the small fungus issue, that I don’t really think affects the image quality.

I’ll take your advice, leave it alone and get a quote for a professional clean.

 

[shutterfinger]

TLR lens are matched in focal length so it will be difficult to get an exact focal length match despite what the marked focal lenght is.
A thread locker that dissolves with acetone was frequently used on lens retainer rings. Acetone based nail polish remover will work and I have never had a problem with it causing problems. Apply liberally around the thread edge of the retainer ring and allow to soak for 5 to 15 minutes, a second application may be needed. The lens barrel may be needed to be clamped in a optical vise to be able to break the ring loose. Placing the lens on a table with a rubber pad between it and the table, putting the spanner in the slots then pressing down with all your weight may work also.