My first try at removing yellow cast on my Takumar

mathab · 04-19-2020, 10:34 PM

Hi y'all, I'm new in this forum (been reading it for months) I just got my first s-m-c takumar 50mm 1.4 with slight yellowing and greasey insides (I suspect it was not treated very well) Just opened it and gave it a good clean. That made me wonder...

1. If I leave the 3 rear elements out in the sun would that be a bad idea?

2. Do you think I could achieve a faster yellow removal than the normal way?

3. In your experience how yellow is this lens?

Very excited to start using the lens, just waiting for the adapter

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MarkJerling · 04-19-2020, 11:22 PM

UV light will de-yellow the lens elements. Some people have reported success using an LED UV lamp: Very little heat to do any damage and no need to disassemble. Plus, likely much quicker than leaving the lens elements in the sun. Still from what I have read, you're looking at many hours even under a dedicated UV lamp to see good results.

**GUB** · 04-20-2020, 01:25 AM

Welcome to the forums. In my opinion that lens is not very yellowed. I think the S.M.C model is less prone than the sup tak 7 element that came before it. Take a look at this thread I started about the subject.
So should I bleach my 50s - PentaxForums.com
Interesting input from people that regret bleaching the lens and other points of view.
I ended up not bothering to do it.

**pepperberry farm** · 04-20-2020, 03:55 AM

I have a Super Takumar 35/2 that was quite yellow - I bought an LED UV lamp (such as Mark mentioned above) from Amazon - sat the lens on the lamp for a day, turned it over for another day - worked like a charm...

mathab · 04-20-2020, 07:59 PM

Thanks for your suggestions. Today I left it in the sun for 4-5hrs then I found a little UV lamp used for curing glue of a screen protector, I think it's too weak cause it's USB and just 3 little leds but don't wanna risk getting the lens too hot. I'll check it in a week to see if it did something.

Can I ideally expect the lens to become completely clear? Or once yellowed it will always have a slight yellow color?

Ronald Oakes · 04-20-2020, 08:26 PM - **1 Like**

The key to using a UV lamp is to get it right on the lens. Even a few inches away will significantly delay and prolong the process.

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04-19-2020, 11:22 PM	#2
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,423	UV light will de-yellow the lens elements. Some people have reported success using an LED UV lamp: Very little heat to do any damage and no need to disassemble. Plus, likely much quicker than leaving the lens elements in the sun. Still from what I have read, you're looking at many hours even under a dedicated UV lamp to see good results.

04-20-2020, 01:25 AM	#3
GUB Loyal Site Supporter Join Date: Aug 2012 Location: Wanganui Photos: Gallery \| Albums Posts: 5,760	Welcome to the forums. In my opinion that lens is not very yellowed. I think the S.M.C model is less prone than the sup tak 7 element that came before it. Take a look at this thread I started about the subject. So should I bleach my 50s - PentaxForums.com Interesting input from people that regret bleaching the lens and other points of view. I ended up not bothering to do it.

04-20-2020, 03:55 AM	#4
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,766	I have a Super Takumar 35/2 that was quite yellow - I bought an LED UV lamp (such as Mark mentioned above) from Amazon - sat the lens on the lamp for a day, turned it over for another day - worked like a charm...

04-20-2020, 07:59 PM	#5
mathab New Member Join Date: Apr 2020 Posts: 2 Original Poster	Thanks for your suggestions. Today I left it in the sun for 4-5hrs then I found a little UV lamp used for curing glue of a screen protector, I think it's too weak cause it's USB and just 3 little leds but don't wanna risk getting the lens too hot. I'll check it in a week to see if it did something. Can I ideally expect the lens to become completely clear? Or once yellowed it will always have a slight yellow color?

04-20-2020, 08:26 PM - 1 Like	#6
Ronald Oakes Pentaxian Join Date: Jul 2017 Location: Virginia Posts: 1,585	The key to using a UV lamp is to get it right on the lens. Even a few inches away will significantly delay and prolong the process.