Archived posting to the Leica Users Group, 2007/11/10

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Subject: [Leica] OT: Fixing radioactive lenses
From: joelct at singnet.com.sg (Joseph)
Date: Sat Nov 10 17:54:54 2007

Jim 

I am traveling right now - will scrutinize my item and advise - I remember
though
that the 8 element type was engraved with a different font from the latter
series - eg
The fig 6 of 5.6 is an open 6 whilst the latter one is engraved with a
closed fig of 6

Check it out and let me know

Joseph Low

-----Original Message-----
From: lug-bounces+joelct=singnet.com.sg@leica-users.org
[mailto:lug-bounces+joelct=singnet.com.sg@leica-users.org] On Behalf Of Jim
Nichols
Sent: Saturday, November 10, 2007 12:33 AM
To: Leica Users Group
Subject: Re: [Leica] OT: Fixing radioactive lenses

Joseph,

I have never been sure how to distinguish the lens model.  My  lens is 
engraved Super-Multi-Coated TAKUMAR 1:1.4/50 and the SN is 5720518. Also, 
ASAHI OPT. CO., JAPAN.  On the back of the Manual/Auto slide is the number 
37902.

If you can enlighten me as to its characteristics, I would very much 
appreciate it.

Jim Nichols
Tullahoma, TN USA
----- Original Message ----- 
From: "Joseph" <joelct@singnet.com.sg>
To: "'Leica Users Group'" <lug@leica-users.org>
Sent: Friday, November 09, 2007 9:22 AM
Subject: RE: [Leica] OT: Fixing radioactive lenses


> Same here and we are referring to the first series with 8 elements ?
>
> Joseph
>
> -----Original Message-----
> From: lug-bounces+joelct=singnet.com.sg@leica-users.org
> [mailto:lug-bounces+joelct=singnet.com.sg@leica-users.org] On Behalf Of 
> Jim
> Nichols
> Sent: Friday, November 09, 2007 4:17 AM
> To: Leica Users Group
> Subject: Re: [Leica] OT: Fixing radioactive lenses
>
> Chris,
>
> You sure lost me!  I'm just happy that my 50/1.4 Takumar does not display
> the yellow cast.
>
> Jim Nichols
> Tullahoma, TN USA
> ----- Original Message ----- 
> From: "Chris Saganich" <chs2018@med.cornell.edu>
> To: "Leica Users Group" <lug@leica-users.org>
> Sent: Thursday, November 08, 2007 2:08 PM
> Subject: Re: [Leica] OT: Fixing radioactive lenses
>
>
>> Well, I'm curious why it even works at all.  In a typical application
>> color is removed from glass by annealing or heating the glass at about 
>> 800
>
>> F for a short time and slowly cooling.  The time and temperature are the
>> main issues and a  look into glass annealing (ie gemstone and color 
>> center
>
>> activation) should shed some light.  Perhaps a slight elevation of
>> temperature for 24 hours?
>>
>> The UV wavelength for A and B are not high enough per se to cause a
>> redistribution of electrons in the atomic valence but UV C does have a
>> high enough wavelength.  The only problem is that is how the color is
>> activated in the first place, by kicking around electrons!  In order to
>> have the process reversed the UV and the glass must have broad energy
>> states in common to cause enough heat  absorption to weaken the existing
>> bonding allowing new lower energy bonds to form eliminating the number of
>> electron radicals in the mix.  Since UV C is more likely to ionize and
>> create electron radicals minimizing the UV C would seem like an idea.
>> Anyway UV C is filtered by the atmosphere so if leaving the lenses in the
>> sunlight works, the UV C isn't the important agent of change.
>>
>> At 12:14 PM 11/8/2007, you wrote:
>>>Thanks Chris
>>>I stopped using the window sill. I've been putting the lens in the
>>>sun when it's bright, but most of the time I've been using a BLB
>>>blacklight bulb. It's only UVA. I don't know which wavelength is most
>>>effective. I could buy a UVB suntan lamp but I won't spend the money.
>>>If what I'm doing doesn't work I'll just continue to shoot b&w with
>>>the lens and be very happy.
>>>
>>>Len
>>>
>>>
>>>On Nov 8, 2007, at 11:16 AM, Chris Saganich wrote:
>>>
>>>>I believe low-E glass coatings suppress infrared, either way those
>>>>coatings don't do much for UV.  The UV you would need to reverse
>>>>the coloration would be quite a bit more then found on a
>>>>windowsill.  About one month continuous 24/7 exposure would do the
>>>>trick.  Best to get a UV lamp and a tinfoil lined box.
>>>>
>>>>
>>>>Chris Saganich, Sr. Physicist
>>>>Weill Medical College of Cornell University
>>>>New York Presbyterian Hospital
>>>>chs2018@med.cornell.edu
>>>>Ph. 212.746.6964
>>>>Fax. 212.746.4800
>>>>Office A-0049
>>>>
>>>>
>>>>_______________________________________________
>>>>Leica Users Group.
>>>>See http://leica-users.org/mailman/listinfo/lug for more information
>>>
>>>
>>>_______________________________________________
>>>Leica Users Group.
>>>See http://leica-users.org/mailman/listinfo/lug for more information
>>
>> Chris Saganich, Sr. Physicist
>> Weill Medical College of Cornell University
>> New York Presbyterian Hospital
>> chs2018@med.cornell.edu
>> Ph. 212.746.6964
>> Fax. 212.746.4800
>> Office A-0049
>>
>>
>> _______________________________________________
>> Leica Users Group.
>> See http://leica-users.org/mailman/listinfo/lug for more information
>>
>
>
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>
>
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
> 



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See http://leica-users.org/mailman/listinfo/lug for more information



Replies: Reply from jhnichols at bellsouth.net (Jim Nichols) ([Leica] OT: Fixing radioactive lenses)
In reply to: Message from jhnichols at bellsouth.net (Jim Nichols) ([Leica] OT: Fixing radioactive lenses)