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UV treatment
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PostPosted: Sat Mar 10, 2007 3:35 pm    Post subject: UV treatment Reply with quote

I am treating two of my lenses with sunlight exposition, in order to attenuate the yellowing caused by the coating.
The lenses are the SMC Takumar 1.4/50 and the Helios-40.

But the process, seems to be very very slow.

So I was wondering, if a UV lamp treatment would help faster. I will be happy to pay some UV lamp sessions for my lenses if this would help.
Are there any side effect (apart from tanning of the barrel) Wink that I should be aware of?
Will UV lamp centers accept to treat metal lenses?
Has any of you ever done or though about doing that?

The fact is that the yellowing really can ruin photographs. My Helios-40 in particular looks like having an orange filter permanently on. I read about that problem with yellowing on old Helios-40 on a website somewhere but I didn't care much, maybe I sohuld have paid more attention, but the fact is, the lens looks so sexy, that I don't want to sell it. I already cured it from fungus, now I really want to de-yellow it, else I'll be forced to use it only for B&Ws.


PostPosted: Sat Mar 10, 2007 3:48 pm    Post subject: Reply with quote

I think it would be cost-prohibitive to go to a tanning salon to have these
treated. To accentuate exposure to the sun: wrap a lens hood in aluminum
foil and place lens in full sun, elevated off the surface it is sitting by a
couple of inches, with rear cap off, of course. You might want to experiment using aluminum flashing (comes in 10" rolls over here for roof
treatments) to make a conical shape that is much larger than what the lens hood could provide.

Why pay for something you get for free?

Bill


Last edited by Katastrofo on Sat Mar 10, 2007 4:49 pm; edited 1 time in total


PostPosted: Sat Mar 10, 2007 4:18 pm    Post subject: Reply with quote

I phoned a retired optical engineer to vet my madness to him and he
concurs, using an aluminum cone over the lens in full sun would greatly
accelerate the bleaching process by capturing more actinics. Placing a
small circular mirror or round piece of the aluminum used for the cone
underneath the rear lens element to where the light would be reflected
back up through the lens would be beneficial, too. One to two sessions
of this in full midday sun would probably do the trick. I don't know if
any birds flying overhead in line with the lens would be incinerated, tho.
I'm kiddin'...I hope. Surprised

Bill


PostPosted: Sat Mar 10, 2007 4:34 pm    Post subject: Reply with quote

katastrofo wrote:
I phoned a retired optical engineer to vet my madness to him and he
concurs, using an aluminum cone over the lens in full sun would greatly
accelerate the bleaching process by capturing more actinics. Placing a
small circular mirror or round piece of the aluminum used for the cone
underneath the rear lens element to where the light would be reflected
back up through the lens would be beneficial, too. One to two sessions
of this in full midday sun would probably do the trick. I don't know if
any birds flying overhead in line with the lens would be incinerated, tho.
I'm kiddin'...I hope. Surprised

Bill


Brilliant idea ! Especially the last sentence Smile I tried to remove fungus with sun , but didn't help. Hopefully yellow thing will be different, but I am afraid it would be long process as Orio said in the first post.


PostPosted: Sat Mar 10, 2007 4:52 pm    Post subject: Reply with quote

Attila wrote:
Brilliant idea ! Especially the last sentence Smile I tried to remove fungus with sun , but didn't help. Hopefully yellow thing will be different, but I am afraid it would be long process as Orio said in the first post.


Well, the engineer I talked to has never tried this, using an aluminum
cone, but he said it should work better than just placing the lens in the
sun. Ideally it would be on a wheel to follow the sun's path but that sounds
more involved. If Orio is in a hurry, he might have to settle with black
and white photos. Wink


PostPosted: Sat Mar 10, 2007 5:53 pm    Post subject: Reply with quote

Orio, I've had a Tak 1.4/50 on my bathroom window cill since the beginning of December. We've had only a little sun since then, low in the sky and the days have been short. Plus the light has to get through two layers of window glass and I'm not here to turn the lens into the sun. Neverthless, the yellowing is a LOT less than it was. I am very encouraged it will be clear in a few weeks.

The lens was probably tucked away in a camera case for years and years, never seeing any light at all. I think it's asking a lot to expect the yellowing to disappear in few days! Have patience Smile


PostPosted: Sat Mar 10, 2007 6:51 pm    Post subject: Reply with quote

I was wondering about a UV light you get for making Circuit boards. When I mentioned it over on the MF forum I was told that it is only sunlight that will do it. As for a turntable to follow the sun how about a mechanical timer swicth?



PostPosted: Sat Mar 10, 2007 8:22 pm    Post subject: Reply with quote

peterqd wrote:
Orio, I've had a Tak 1.4/50 on my bathroom window cill since the beginning of December. We've had only a little sun since then, low in the sky and the days have been short. Plus the light has to get through two layers of window glass and I'm not here to turn the lens into the sun. Neverthless, the yellowing is a LOT less than it was. I am very encouraged it will be clear in a few weeks.

The lens was probably tucked away in a camera case for years and years, never seeing any light at all. I think it's asking a lot to expect the yellowing to disappear in few days! Have patience Smile


Very good news ! I cross my fingers Orio, good luck!


PostPosted: Sat Mar 10, 2007 11:34 pm    Post subject: Reply with quote

Thanks Bill. I'm not sure if we have that aluminium flashing here (I never saw roofs made with aluminium), but the suggestions that you made are very interesting. For sure I will try to build a cardboard cone with aluminium sheet inside (the one for cooking. Maybe it can also work). And the mirror suggestion sounds great, too.

Hopefully it will also work the other way around, as for isntance I expose the rear glass of the Takumar, since it's the rear glass in that lens that appears to be yellowed.
With the Helios the mystery is deeper, because both the front and rear glass appear bluish, yet, the result is a dense yellow image - so i suspect that the yellowing is caused by some inside glass element (and i know there is a lot of glass inside a Helios-40).


PostPosted: Sun Mar 11, 2007 12:08 am    Post subject: Reply with quote

Sorry to hear your troubles, Orio, sounds like a headache. I was surprised
it was an SMC Tak with this yellowing. I have a Super-Tak that is older,
that doesn't have this vaunted multi-coating. Hummm.

The flashing (aluminum roll) I mentioned is used around chimneys on
roofs, and in northern climes on the eaves-side edge where icicles would
damage the shingles. Aluminum foil from the grocery store should work
just fine, molded to a cardboard form. Good luck!


Bill


PostPosted: Wed Sep 26, 2007 4:25 am    Post subject: Reply with quote

If you really want to speed up the process, find a buddy that works in a Printing Shop, and put it in their metal plate burner. Very high UV and not too warm.

Kiron kid


PostPosted: Wed Sep 26, 2007 1:18 pm    Post subject: Reply with quote

Hi!

I have a UV-lamp (originally meant to be in a terrarium) in my lens cabinet which I switch on every two or three weeks for a short while. But not because of yellowing but to fight fungus spawn which flies around inside (like everywhere).

UV light does not really help against the fungus inside a lens. The thing is that lenses consist of glass Wink which stops a considerable percentage of UV light anyway. (This is why you won't get a sunburn behind a windows as fast as if you're outside.)

But if you treat the glass itself, UV light will most probably help.