Sticking Apature Cure?

photoman · Mar 13, 2004

I have a mamyia sekor lens, 55mm 2.8 that has what looks like an oily residue on the apature blades. When I stop down the lens the blades go into place i beleive on time with the shutter but when they are released they get stuck and dont want to come back to wide open really quickly.
I've tried exercising the lens apature thinking it would help the problem but to no prevail it didnt do anything.(The apature not coming back has a real problem for focusing at low light)

Does anyone know what this residue could be?

Would it be worth fixing it, buy a new used lens, live with the problem, or try some self repair (never took apart a lens before)

Any advice would be appreacaiated

ksmattfish · Mar 13, 2004

Old gummy oil on the blades. I would imagine that replacing the lens would be cheaper than repair. Taking apart lenses intimidates me. Home repair is a gamble so I would only do it to a lens that I can afford to wreck.

markc · Mar 13, 2004

If you are serious about doing any repair yourself, you might want to check out Ed Romney's stuff.

ksmattfish · Mar 14, 2004

The Mamiya Sekor, while a perfectly good camera, isn't particularly hot on the used market, so they go cheap. You may have to buy a body attached to the lens you want, but I bet it's pretty cheap anyway.

markc · Mar 14, 2004

Yeah, I picked up a 1000DTL off eBay for something like $40, including a 55mm 1.8 lens. You're talking about an M42 mount, right?

Since it's already useless to you, it sounds like a good candidate to give up it's life for the sake of experimentation if you wanted to mess with it yourself.

oriecat · Mar 14, 2004

Yay! More Mamiya/Sekor users! I've got 3 of them. Two have broken light meters, but whatever... hey Mark... my first two were 500TLs and now I got a 500DTL. So can you tell me what that little slider button that goes from S to A is for? The TLs don't have that, and I can't really tell what it's doing when I switch it, other than moving the needle inside...

markc · Mar 14, 2004

Erm...
*wracks brain*
"Spot" and "Average", I believe.

I haven't used it much myself. It's "on loan" to a friend who couldn't afford one.

oriecat · Mar 15, 2004

That makes perfect sense! Thanks!

paul rond · Mar 15, 2004

http://www.kyphoto.com/classics/forum/

Try asking your question on this site. They are dedicated to DIY repairs on old cameras. Many of the people there are retired repairmen and can explain exactly how to open and clean it properly. I only repair MF Mamiya RBs not the 35mms.

One quick fix can be to put the lens in a warm place to loosen up the old lubricant but I would dismantel the lens and clean it out with a wash of naptha (white gas) or lighter fluid is also a good degreaser. Can you remove all the glass?

A tip... when removing the glass... put a small magic marker dot on the face side of the each element as you remove them. It's very easy to put em back in backwards.