how to fix/clean 'frozen' lenses?

Post by **tgreathead** » Fri Feb 27, 2004 2:02 pm

I have a lens for my Keystone A-12 (16mm) that is stuck at it's present settings. I have worked it a little to release the iris a bit, but the focus is locked. Any ideas on how to get it loose?

Thanks,
--Taylor

Post by **camera8mm** » Fri Feb 27, 2004 4:41 pm

oil works. so does dipping it in rubbing alcohol, if there's fungus.

Post by **perthskydiver** » Fri Feb 27, 2004 4:51 pm

absoloutely not....
I'm employed as a camera repairer, although I dont specialise in lenses, one of our other tech's does & i've learnt a fair bit from him.

oil, alcohol, WD40 should never ever be used, sprayed or dipped onto a lens. more than likely the aperture blades are stiff due to muck build up between the blades. you could prob free it up externally by slowly & gently at first moving the aperture ring back & forth. but to repair it properly, basically must be disassembled (usually from the rear mount) aperture section removed THEN & ONLY THEN YOU MAY SPRAY OR CLEAN THE BLADES WITH CONTACT CLEANER OR ISOPROPANOL. trying to do this whilst the lens is assembled from the exterior will only ruin your lens...

Post by **MattPacini** » Fri Feb 27, 2004 7:15 pm

I have just the opposite problem:
I have a nice Zeiss 70-300 zoom, but the focus tube just sort of "floats" if I have the camera pointed up or down.
Any idea what's causing that, and how I can fix it?
I'm scared to death of disassembling the lens.

Matt Pacini

Post by **studiocarter** » Sat Feb 28, 2004 11:39 am

Some lenses are not supposed to move even though they are marked as if they do.

Try putting the lens on a sunny window sill for a while. That usually loosens up the grease so you can get it moveing again. I once tried the oven set at a very low setting and loosened the lens that way but also made the lens coating spotty or come loose a little, so don't do that. Unless it is an old uncoated type.

Post by **perthskydiver** » Sat Feb 28, 2004 5:54 pm

Putting it in the sun will loosen it up, generally only temporarily though. Once it gets cool & dry again the grease will stick yet again...

As for your problem Matt, sounds like it will need to be disassembled for it to be repaired. I prob wouldn't try it, unless your not worried about putting the lens back together. Lenses can be a nightmare to work on. Very few people actually repair lenses so it very specialised & usually pricey$$ repair costs.....

Post by **Brackish** » Sat Feb 28, 2004 10:43 pm

I have a lens where the aperture blades are stuck. What would
be a good oven temperture, that won't
ruin the lens?

Post by **perthskydiver** » Sun Feb 29, 2004 3:58 pm

lol... your only joking about the oven right??

Post by **Brackish** » Sun Feb 29, 2004 6:58 pm

Aside from sending it in for disassembly/cleaning, which probably
would cost more than buying a new lens, what would *you* do?
Perhaps 1 hour @ 200 degrees F?

Post by **perthskydiver** » Mon Mar 01, 2004 4:41 pm

no I would definetely not place it in the oven for any given time... I've never heard of that one before. I told the lens tech at my work about it & he laughed..lol.
If the reason your wanting to place it in the oven is to melt the muck & grease on the lens it wont work properly. Once the lens goes cool again, it will only freeze up again. Like I said, the only way to do it properly is to dismantle it... Try it yourself, you have nothing to lose except a broken lens... Just write down what goes where & take macro digi photos of each stage of disassembly so you know how to re-assemble it again.
Good luck...

Post by **studiocarter** » Mon Mar 01, 2004 7:36 pm

It was overcast that day, so the oven on low low was tried just to disasemble the lens; it did work but hurt the lens coating; it didn't get very much warmer than a lens in the sun so don't do it.
Cine Kodak lenses are easy to clean. When you unscrew them and the two parts part you must mark the position so you can thread them back together starting on the proper thread. That is the only way you will ever get them to focus properly; trial and error will be needed to get them back together properly if you loose that twist. The grease is usually Molibdamum (sp) it is white. All the old grease is removed and the threads cleaned out and some new is put on. Frozen B8 lenses like the 36mm D mount was easy to clean up and get moveing again.

Some lenses are not supposed to move either the aperture or the focus; they are preset to hyperfocal settings for general use. So if they don't move it may be because they are purposed to be used outside in bright light.