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Shootar401
20-Dec-2012, 20:36
Can a normal black light such as the kind you find at Home Depot or Lowes be used to bleach the rear elements of an Aero-Ektar lens? Or will I need some special UV light source?

Thanks

john wilton
20-Dec-2012, 22:18
I put a compact fluorescent backlight bulb from home depot in a reflector and suspended it over a yellow 35/1.4 nikkor (first version0; after a weak the yellow was gone.

joselsgil
20-Dec-2012, 22:22
I was recommended to leave the lens in the sunlight. I have not tried it just yet as the lens and shutter are still being repaired.

john wilton
20-Dec-2012, 22:33
The heat buildup involved with prolonged exposure to ever-moving sunlight cannot be good for the lens and its mechanical parts. Blacklight recommended.

jcoldslabs
20-Dec-2012, 23:38
I was able to clear a severely browned/yellowed Aero Ektar with a CFL black light. I positioned the light directly over the rear element and put a mirror under the front element to maximize the amount of UV passing through the glass. Took a few weeks but there was hardly a trace of discoloration once I was finished.

I tried sunlight for a brief time but I wrapped the lens barrel in tin foil to keep the heat down a bit. I would say a bulb is a safer (but slower) option.

Jonathan

John Kasaian
20-Dec-2012, 23:44
Awww, the yellow glass gives it character!
For piece of mind have it checked at the nuclear medicine lab at your local hospital.

Sevo
21-Dec-2012, 00:44
Blacklight or nail polish hardening lamps are perfectly fine, indeed best for the job, as energy in the range from deep blue to near UV is what you need. If nothing else is at hand, 6500K fluorescent will do better than mid or far UV.

lenser
21-Dec-2012, 04:07
Does this also work to destroy fungus?

Sevo
21-Dec-2012, 05:48
Does this also work to destroy fungus?

No! That is, fungus doesn't thrive in well-illuminated places, and UV-A behaves quite like visible light when it comes to that - but these conditions only hinder growth, and won't kill the spores. For sterilization you'd need UV-C or at least short wavelength UV-B. Safety issues aside (both cause cancer and can blind you), I strongly doubt that UV irradiation is a appropriate solution for fungus infested lenses - glass is opaque to the shorter UV (B and C) wavelengths, so you'd have to disassemble the lens to isolate each element and irradiate it from both sides. Besides, effective wavelengths will also bleach paints and destroy rubber and plastics - effects that are generally not welcome on a lens.

jk0592
21-Dec-2012, 08:36
Wouldn't a yellow tinted lens act as a "built-in" yellow filter useful for b/w ?

Dan Fromm
21-Dec-2012, 10:45
jk, the tint reduces transmission.

shootar, second john wilton's suggestion. I've used a 20w BLB compact fluorescent to clear a number of yellowed lenses. A couple of TTH apo-tessars (badged Apotal, Cooke Copying Lens, TTH Copying Lens) and a Repro-Claron. Clearing them took around a month.

I wouldn't put a lens out to bask in the sun. Too much crud, not to mention rain, will fall on it.

Mark Sawyer
21-Dec-2012, 11:04
I keep mine indoors on a west-facing windowsill, rear elements towards the afternoon sun with the fronts covered so they don't start fires.

Shootar401
21-Dec-2012, 12:38
I picked up a CFL black light and a 5" reflector and have the light and lens in the corner of my desk. I'll check it every week and see how it goes.

EdSawyer
21-Dec-2012, 16:31
I use a UV LED flashlight. Works well. The last AE I did took a few weeks @ 24/7. They will fully clear though, which is nice. The one taking forever at the moment is a 6" f/2.5 Bell Howell lens. Has at least 3 elements with radioactive browned glass. (out of 8 or 9 elements total).

Sevo
22-Dec-2012, 04:51
Has at least 3 elements with radioactive browned glass. (out of 8 or 9 elements total).

Well, be patient. Or take it apart to increase the amount of UV the inner elements get.

EdSawyer
24-Dec-2012, 08:28
I did disassemble it for cleaning already, but put it back together for the bleaching. May take it apart again if I get impatient but I have other things to use in the meantime so I am not in a huge rush. I still haven't figured out how to mount it yet .