Tech Lenses and Dust

[rga]

After returning from a week in the eastern Sierra Nevadas, my tech lenses (Schneider APO Digitars) had a lot of dust in between the elements. I sent them back to the dealer and just got them back after a cleaning (pristine now, fortunately!). We think the dust may have entered through the shutter cocking slot or elsewhere; the elements are well sealed to the mounting plate.

Does anyone have any techniques for keeping dust out of these lenses? Please don't respond to not use them in a dusty environment... I really only shoot landscapes and won't be able to avoid dust in some of the venues I'm going to (Death Valley, Monument Valley, etc.).

Any advice very much appreciated,
Bob

 

[GrahamWelland]

I don't have a solution to the problem but I can certainly concur with what you've found. I had the same thing happen with my SK 150 the first time out with it in Monument Valley where after the first morning I found a couple of dust spots between the elements plainly visible to the eye. It also permeated into the thread of the helicoid too although the good news is it isn't visible in images or a roughness problem using the lens. The worst thing would be really that it increases the possibility of flare. I figured it had to be the shutter because there's basically no other way between the elements that I'm aware of. Superficiallly everything else looked pristine.

Presumably your dealer just disassembled the front element from the shutter assembly and blew it out? I certainly wouldnt want to touch anything like that myself and hence why I decided that I'd wait until it was bad enough to warrant a service.

 

[vjbelle]

I've had one of my first 35mm lenses apart. Its just like any large format lens.... both the front and back unscrew from the helical. I assume that is what your dealer did and then blew/dusted out the contamination. It really is good, though, to have this type of information. I think a little extra care is worthwhile when out in windy/dusty conditions.

Victor

 

[rga]

I've had one of my first 35mm lenses apart. Its just like any large format lens.... both the front and back unscrew from the helical. I assume that is what your dealer did and then blew/dusted out the contamination. It really is good, though, to have this type of information. I think a little extra care is worthwhile when out in windy/dusty conditions.

Victor

Thanks. It's even better to know that the 35 is user cleanable for this situation. So thank you!!

 

[Woody Campbell]

I've had one of my first 35mm lenses apart. Its just like any large format lens.... both the front and back unscrew from the helical. I assume that is what your dealer did and then blew/dusted out the contamination. It really is good, though, to have this type of information. I think a little extra care is worthwhile when out in windy/dusty conditions.

Victor

Victor - thanks. Just like the old days. Just tried it on mine and no problem.

 

[f8orbust]

I've had all my lenses apart to clean them - the front and back groups that is, unscrewed from the copal shutter, not the groups themselves. As long as you're careful not to lose any factory installed shims, or cross a thread screwing them back in there shouldn't be a problem. You can also mark (e.g. using small bits of sticky paper with pen marks on) the position of each group in relation to the copal shutter, and that way when you screw them together again you can make sure everything aligns correctly.

 

[rga]

I've had all my lenses apart to clean them - the front and back groups that is, unscrewed from the copal shutter, not the groups themselves. As long as you're careful not to lose any factory installed shims, or cross a thread screwing them back in there shouldn't be a problem. You can also mark (e.g. using small bits of sticky paper with pen marks on) the position of each group in relation to the copal shutter, and that way when you screw them together again you can make sure everything aligns correctly.

Excellent suggestion about the alignment. Thanks!