Super Takumar 50/1.4 - Leave Yellow or Not?

wlewisiii

wlewisiii

Just another hotel clerk
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I found a fairly inexpensive Super Takumar 50/1.4 on Eprey. It's the second version, 7 element thorium glass kind. The seller described it as filthy but working fine. Ok, that's cool. I can clean a lens. I get it and its cleaner than most lenses I've gotten. It is, however, well yellowed as most thorium glass lenses tend to be and I wonder if the seller thought that was something that required cleaning?

So the question becomes do I leave the built in yellow filter in place or sun bleach it out? If I leave it, what filter factor should I use? I hand meter as the body this is on, my Honeywell Pentax H1a, is meterless.

Thoughts?
 
I used once Super-Tak 35/2 that was so yellow it made color pictures on Kodak almost impossible to fully correct. Now I have Super-Tak 50/1.4 and I bleached it with UV lamp, not fully but only effect I observe is a slight tint in the viewfinder. I'd meter the very yellow one as a stop slower, but I meter mine as f/1.4.
 
I have a Canon FD 35/2.0 with thorium glass that has yellowed. I shoot a lot of B&W film, so have kept the lens as is. If you shoot a lot of color, you might want to give your lens a UV treatment.

Jim B.
 
It's probably a Yellow-1 filter, probably 2/3rds stop?

I bleached the yellow out of all three of mine. Unscrew the rear group, put in a wooden box with a UV light. Do not use UV-C, it cannot penetrate the glass. UV-A and UV-B can penetrate the glass, bleach out the yellow in a couple of days. Unscrewing the rear module means the lubricants of the lens are not heated up.
 
Might just leave this as a B&W only system. I have plenty of other cameras for color, even color film. I'll ponder that for a bit but if I do go with bleaching it, I'll remember that about the rear module.
 
wlewisiii said:
I found a fairly inexpensive Super Takumar 50/1.4 on Eprey. It's the second version, 7 element thorium glass kind. The seller described it as filthy but working fine. Ok, that's cool. I can clean a lens. I get it and its cleaner than most lenses I've gotten. It is, however, well yellowed as most thorium glass lenses tend to be and I wonder if the seller thought that was something that required cleaning?

So the question becomes do I leave the built in yellow filter in place or sun bleach it out? If I leave it, what filter factor should I use? I hand meter as the body this is on, my Honeywell Pentax H1a, is meterless.

Thoughts?
Click to expand...
I kept mine yellowed for years, it was fine in BW but you lose at least 1 stop and it is not really yellow is more tabac

At some point I decided to give the Ikea lamp hack a chance and the result was pretty amazing. So Yes, do clean it
 
titrisol said:
I kept mine yellowed for years, it was fine in BW but you lose at least 1 stop and it is not really yellow is more tabac

At some point I decided to give the Ikea lamp hack a chance and the result was pretty amazing. So Yes, do clean it
Click to expand...
Which Ikea lamp?
 
Hmm, that thread implies that a simple bright LED lamp (no heat, no UV) is sufficient in itself. Eh, I'll give that a try starting overnight and see what happens since I have such a lamp and bulb already to experiment with. If it works, cool; if not, nothing lost.
 
It seems that a bright LED lamp really will clear away yellowing. Yay.

And expose threads of fungus. Boo.

Not especially bad but I'll need to probably get the UV lamp after all to kill it and then open the back module (looks like) anyway to clean it. Bummer.

Such is life.
 
wlewisiii said:
Hmm, that thread implies that a simple bright LED lamp (no heat, no UV) is sufficient in itself. Eh, I'll give that a try starting overnight and see what happens since I have such a lamp and bulb already to experiment with. If it works, cool; if not, nothing lost.
Click to expand...
Yes, those were the findings of the US military in the 1950s-60s-70s

Effects of ionizing radiation on selected optical materials: An overview (Technical Report) | OSTI.GOV

The U.S. Department of Energy's Office of Scientific and Technical Information
www.osti.gov www.osti.gov
 
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