Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-10-2009, 03:30 PM   #16
Veteran Member
Lloydy's Avatar

Join Date: Aug 2007
Location: Shropshire, UK
Posts: 1,114
Would the light that people use to help with SAD syndrome work as well?

03-10-2009, 03:54 PM   #17
Forum Member




Join Date: Jan 2009
Location: Pleasanton, CA
Posts: 68
QuoteOriginally posted by SOldBear Quote
No need to take the lens apart. I sure didn't. This week is sunny in Pleasanton. It should not take more than 2 days for your lens.
Thanks - I am not having the problem AFAIK, but maybe I just need to look more. This is really just a curiousity for me and goes along with my LED lights hobby. That is why I asked if anyone had an old yellow lens I can borrow to test it out - then return it.


QuoteOriginally posted by Lloydy Quote
Would the light that people use to help with SAD syndrome work as well?
I don't think so, but then again, I have not really looked into the photon energy required either. Obviously there is some kind of photochemcail reaction occuring, but I am still unclear on exactly what it is. I would have originally guessed that it is the adhesive holding the glass elements together yellowing, but others report that it is the glass itself, so I am not sure.

I was going to first use 455nm (royal blue) to see if this works, then move down to 405nm (near UV) if needed. There are 365nm (UV ) LEDs out there, but since the UV lamp worked for Ovim, this is probably not needed.

Last edited by HarryN; 03-10-2009 at 04:12 PM.
03-10-2009, 03:59 PM   #18
Loyal Site Supporter
monochrome's Avatar

Join Date: Mar 2008
Location: Kirkwood (St. Louis) MO
Photos: Gallery | Albums
Posts: 20,202
QuoteOriginally posted by k100d Quote
I tried Brian's method first, but the glass was still yellow -
03-10-2009, 04:01 PM   #19
Loyal Site Supporter
monochrome's Avatar

Join Date: Mar 2008
Location: Kirkwood (St. Louis) MO
Photos: Gallery | Albums
Posts: 20,202
QuoteOriginally posted by cpopham Quote
Something tells me your directions might not work so well for me.....
Ahhhh - another case of hemisphere-centrism exposed!!

And we thought Religious and Political threads were a problem.

03-10-2009, 04:40 PM   #20
New Member
tinyt187's Avatar

Join Date: Feb 2008
Location: San Diego
Posts: 11
Touche!

QuoteOriginally posted by k100d Quote
This is outstanding, I feel like I've been Rick Roll'd. Well Done.

I am however extremely happy to know that I'll soon be able to use the Takumar 50mm 1.4 that I had written off as toast a couple of years ago!

Thx everybody!
03-12-2009, 04:52 AM   #21
New Member




Join Date: Mar 2009
Posts: 19
I got a deal on a 50 1.4 on ebay because the seller hadn't noticed the yellowing, i think its only slight, so im now waiting for my fastest lens to arrive from the states! Does anyone have any ideas about a UV torch that would work for clearing the yellow? I also wondered about one of those pieces of kit they use to check ID in bars, but havent really looked into it.

Cheers
Rowan
03-12-2009, 05:36 AM   #22
Senior Member




Join Date: Feb 2009
Posts: 228
I am a little tired the yellows lenses. there is a pile of lenses with that problem Pancolar 1.8/50, CZJ 2.8/180, s.t.2/35, etc.
With my 11 w - lamp UV of ticket detector - takes long time.

At direct sun or powerfull UV lamp.
03-12-2009, 08:48 AM   #23
Veteran Member
jamonation's Avatar

Join Date: Jun 2008
Location: Toronto
Photos: Gallery
Posts: 364
This is a good page describing various attempts with UV lamps to de-yellow lenses: orly going thirty: The Blue Light

03-12-2009, 01:57 PM   #24
Site Supporter
germar's Avatar

Join Date: Apr 2007
Location: Austin Texas
Photos: Gallery
Posts: 728
I've used my wife's "Aerogarden" hydroponic gardening kit...I just set my 35mm f2 SMC Tak right next to the Basil, and in a few weeks I turned it over....another couple of weeks and it was clear.
Here's a link to an article about these yellowed radioactive lenses
03-12-2009, 07:33 PM   #25
Junior Member




Join Date: Feb 2007
Location: near Brisbane, QLD
Posts: 49
QuoteOriginally posted by rowan57 Quote
I got a deal on a 50 1.4 on ebay because the seller hadn't noticed the yellowing, i think its only slight, so im now waiting for my fastest lens to arrive from the states! Does anyone have any ideas about a UV torch that would work for clearing the yellow? I also wondered about one of those pieces of kit they use to check ID in bars, but havent really looked into it.

Cheers
Rowan
I had success with a UV flashlight SKU 01300 from Dealextreme.com.

I made up a tube to mount it to the screw side of the lens and laid a layer of aluminium foil inside the lenscap.

On a constant feed of rechargable AAA batteries, it took about 4 days to clear the yellowing.

Cheers
Geoff
03-12-2009, 09:30 PM   #26
Inactive Account




Join Date: Mar 2008
Location: France, EU
Posts: 97
QuoteOriginally posted by ovim Quote
I cleared the yellowing from my S-M-C Takumar 1.4/50mm recently with a energy saving UV bulb in only 24hrs.

The trick was to dismantle the lens so that there was no glass (to block the uv-rays) between the yellowed element and the uv-bulb
....

Dismantling the lens is not that hard (there's instructions on the net) but you need a clean workspace, some tools, patience and it's good to make notes (and/or take pictures) to remind you how everything was. Usually there will be couple of small dust particles left inside the lens no matter how careful you are (I can live with that).

...
One thing I don't understand from your explanation: why do I have to dismantle the lens ? The other lens elements are not opaque so the UV light can easily pass through to reach the yellowed element. Maybe it won't take only 24hrs, you can leave it for 10hrs more, but at least you don't have to compromise the lens assembly (when you dismantle a lens, you'll not be able to put them exactly calibrated as before... you'll need a special laser device to align them perfectly).
03-12-2009, 11:15 PM   #27
Pentaxian
ovim's Avatar

Join Date: Sep 2008
Location: Tre, Finland
Photos: Gallery
Posts: 1,227
QuoteOriginally posted by huqedato Quote
One thing I don't understand from your explanation: why do I have to dismantle the lens ? The other lens elements are not opaque so the UV light can easily pass through to reach the yellowed element. Maybe it won't take only 24hrs, you can leave it for 10hrs more, but at least you don't have to compromise the lens assembly (when you dismantle a lens, you'll not be able to put them exactly calibrated as before... you'll need a special laser device to align them perfectly).
I had bought the lens as defective (few missing screws, dirt inside) and I had opened it before and it worked flawlessly (or at least good enough for me) after that. On an other forum a member reported doing this de-yellowing many times and told me it would take 2-4 weeks with a 15W UV-bulb. So I wanted know if I could speed up the process. I knew that normal window glass blocks a lot of UV-rays and some types of glass doesn't block them at all. So I wasn't sure if it would help but I wanted to try. I'm not an optical engineer and you might be right about the calibration, but for me the lens works just fine.

I've got a near-mint SMC-A 1.7/50mm and the IQ is on par with it (with it's own characteristics of course)

Last edited by ovim; 03-13-2009 at 02:05 AM.
03-13-2009, 12:16 PM   #28
Senior Member




Join Date: Feb 2009
Posts: 228
I wan't any yellowish lens anymore!!

I'm sorry that anyone have one of this.

all the versions of Pentax M42 1,8/55 is better, for me, than the A 1,7/50. I like the first very much. Only better Pancolar 50.

And the 1,4/50 is a real dream. I think that eliminated the yellowish cast (or yellow color in some cases), let to the lens show all his capabilities.
12-26-2010, 11:37 AM   #29
New Member




Join Date: Dec 2010
Posts: 1
Salut,
j'aimerais réprende le subject pour connaître vos résultats...
je suis en train de traiter deux f1,4 et aussi un f2, j'ai essayé longtemps avec une lampe UV qui donnait une lumiére trés blanc sans presque aucun résultat aprés environ 200 heures d'exposition.
Maintenant je laisse les objectifs au soleil (pour l'instant il semble que le chaleur n'affecte pas le lubrifiant) et ça a l'air plus effectif, mais peut-être a cause de ne pouvoir pas ovrir la fenetre la plupart de lumiére UV est perdue.

Je voudrais savoir si c'est seulement un element en particulier qu'a le jaunissement et aussi si l'essai avec des lampes led a donné des résultats ou pas...

bonne journée a tous.
04-04-2011, 08:55 PM   #30
Site Supporter
mikeSF's Avatar

Join Date: Jan 2009
Location: East Bay Area, CA
Photos: Gallery
Posts: 5,680
i'll bump this thread to say that i had acquired a yellowed Super-Tak 50/1.4 sometime ago and finally decided to follow the instructions provided to de-yellow-fy it.
I placed it in the window out of the way, wrapped in foil(very important) and also within a ziploc bag to keep the dust off. It was winter, plus my windows are all treated with Low-E or Gila UV blocking film, so i knew this would take longer. Well, i just left it there for about 6 weeks and looked at it today and was amazed that the dark yellow tint is completely gone. I wouldn't be surprised if i gained back a stop of light.
cool!

PS - i had the rear element facing toward the light.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
k-mount, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Yellowing Super-Tak == SMC? slrl0ver Pentax SLR Lens Discussion 21 11-16-2012 10:29 AM
Takumar 200mm F3.5 question eccs19 Pentax SLR Lens Discussion 3 08-24-2009 03:16 PM
Takumar Question eccs19 Pentax SLR Lens Discussion 11 12-25-2008 05:53 AM
SMC Yellowing... migz55 Pentax SLR Lens Discussion 2 02-09-2008 11:04 AM
Getting rid of yellowing? How? jsherman999 Pentax SLR Lens Discussion 18 01-29-2008 05:34 PM



All times are GMT -7. The time now is 07:33 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top