[condor27596]

I would like to get a UV bulb that can be used to perform preventative maintenance on my good lenses and can also remove the yellow from my radioactive lens.

I generally use Amazon and eBay.

Thanks.

[Dlanor Sekao]

I would like to get a UV bulb that can be used to perform preventative maintenance on my good lenses and can also remove the yellow from my radioactive lens.

I generally use Amazon and eBay.

Thanks.

I use cool weather direct Sunlight or a Daylight bulb from Home Depot that has UVA and UVB.....I think they cost about $7 and are also called "Full Spectrum".....You don't need some special "Photo Branded" over priced bulb. I believe they are rated at Like 5300-5500 Kelvin ? They are a Fluorescent ....not a regular screw in incandescent bulb.

[Not a Number]

I believe people have used the UV "Party" bulbs that are available at Home Depot and Lowes. They take longer but do the job.

[condor27596]

I have a compact fluorescent black party bulb. I can let it run all night at work. Is this ok ?

[Not a Number]

You may have to run it several days. Just check it periodically to see how the yellow is clearing.

[condor27596]

Days is fine. I can leave it weeks at work.

[dclauria]

I also used a CFL compact fluorescent black light screw in bulb from H.D. in a small gooseneck table lamp. It seemed to do the trick.

[southlander]

Explore an aquarium shop, they have also sorts of special bulbs to encourage underwater plant growth, coral growth etc. although I can't recall off hand what parts of the spectrum gets enhanced. Been a long time since I last dabbled in aquaria.

[Dlanor Sekao]

Light Bulbs Etc, Inc. 23 Watt Compact Fluorescent T3 / 5500K / Medium Base


Keep it within a few inches (5-6) to work. Most people don't realize that it has to be very close. You want something that has at least a 90 CRI....the higher the CRI Rating the faster it works ! However at the same time , the Higher the Kelvin rating also generally emits more heat so you DO NOT want to bake your lenses.
Older manual Lenses don't like to get hot as it can dissipate the grease inside and it may solidify/condense on the aperture blades making them sticky. Keep the distance close but not so close that it exceeds 95 degrees. If the lenses get too warm just put a small fan close to them on low to dissipate the heat. DO NOT exceed 5500 Kelvin and DO NOT use any bulbs with a rating of 6000 to 6500 Kelvin.....they are too hot and will bake your lenses.
I de-yellowed several Takumar lenses with something very similar as above from Home depot but the rating was 92 CRI.
Buy a Quality Name Brand and not some Chang-Fu china crap that emits God Knows what ???
I still say there is nothing like good old-fashioned unfiltered sunlight during cooler weather dealing with Yellowed Takumar lenses but it will take a lot longer.

[condor27596]

Than is a full spectrum. I thought I needed uv ?

[Nass]

Hi DC,

Have you seen somewhere a writeup about the UV this produces? I'd be interested... thanks

[Dlanor Sekao]

Than is a full spectrum. I thought I needed uv ?

It IS.....its the closest thing to natural Sunlight .....UVB Spetrum.

---------- Post added 05-12-15 at 10:26 PM ----------

Actually I never have read anything about de-yellowing a Takumar anywhere......ever.
I learned it from a Student at Arizona State University west campus in Peoria Arizona from the Arts Department. He said that's what he learned to use on some old lenses at home.
I have a past history of using Full Spectrum Lighting from a Herpetoculturist's standpoint rearing hatchling Reptiles and had several bulbs to play with. All I can tell you is this....It works much faster than natural sunlight. I have used it on appx 10 lenses that I bought for resale .... It Works !

[Ontarian50]

Yes, I've used the Janso light on several Takumar lenses and one Hexanon. Some clear quicker than others. A 105mm Super Takumar for a Pentax 67 looked like it had a 85a filter on it until it was treated for a few days. Still had a slight yellow tint, but obviously much improved. Certainly much easier than trying to aim a lens at the sun in the back yard.
There may be some benefit to removing the rear group and lighting from both sides (flipping every day or so) because it's usually just the rear half of the lens that's affected.

[condor27596]

That fluoresant bulb looks nothing special. Can I use one I have ?

[Not a Number]

Try the bulb you have. You can always resort to the sunlight cure or buying the lamp from Ikea. Those make handy light sources for table top macro work.

Everything I've read said it is UV light that does the clearing, although one paper says heat will also reverse the coloration - so putting the lens in direct sunlight would give UV exposure and warm the glass. Everything I've read says the party black light bulbs will work although some people say it took weeks. I talked to a friend who has a Takumar f1.4 lens and he said he cleared it with a party lamp, it took about 3 days. Sunlight can take 1-2 weeks. Much of it depends on the lens and the amount of discoloration.

Quote: As I understand the process, UV photons will allow electrons to overcome a potential barrier and eliminate the color centers causing the brown color.

https://web.archive.org/web/20060813134321/http://www.medfmt.8k.com/mf/radioactive.html