Accessing rear element for fungus cleaning - Electro 35 GTN

[freecom2]

Hi all,
The rear elements on my new-to-me GTN appear to have a fair bit of fungus on it. Normally I would leave it but this would be a fun DIY project.

Most of the disassembly guides on the net talk about removing the front lens assembly, all to get to the shutter. Most of them don't go any further. I've tried to have a look at the service manual but scribd is a bit unreliable!

So is it a case of taking apart the whole camera essentially? And what is the preferred chemical for treating fungus?

[nparsons13]

I believe the way to the rear element is from the rear (the inside) of the lens mount after you've detached it from the body, just as you do to access the POD. You'll need a solid, well-fitting lens spanner to unscrew the rear lens ring without risking a scratch to the lens. Maybe cover the lens with masking tape before attempting the removal.

I've never been successful at removing fungus from lenses; they've always been etched. Florida fungus must be stronger than other strains.

Instructions for removal are at http://herron.50megs.com/fungus.htm and other places on the web. Good luck.

[freecom2]

Thanks for the tips, very much appreciated! I too am worried about potential etching.

[Blanc]

from the back it will be a mess.

from the front you just have to remove the name ring, unscrew the front element, opent the shutter on bulb and the diaph at it's max and clean.

Remind to pre-wash the fungi with some acetic acid (4%) it moltens the thing up and reduce the risk of scratching the glass, then some Eclipse or other cleaning agent and a good (clean, just out of the box!)lens tissue, and this should be ok.

even if the fungi had left a little mark in the glass there should be no real impact on the pictures (as there is really few impact with the fungi) due to the lens formula.

[Frontman]

Accessing the inside of the lens should be done as Blanc said. I have serviced a few dozen Yashica cameras, and have found that fungus rarely etches Yashica glass (with Canon glass the opposite is true, it is nearly always irreperably etched). Usually you only need to use a cotton swab and regular lens cleaning fluid. For tougher fungus, I will also use a touch of toothpaste.

[freecom2]

Thanks for the insights guys - glad to hear that the chances are, it hasn't been etched.

Frontman, "regular lens cleaning fluid" - as in the stuff people use to clean a dirty front element sort of fluid? If so, it would save having to find some hydrogen peroxide/ammonia...

[farlymac]

Athletes Foot cream works too. Get it at the dollar store, as you don't need to spend a lot for the same effect. Even the oil on your nose will work.

PF

[freecom2]

I ended up buying some white vinegar to use instead - fingers crossed. Will get down to it in a few days time.