Jesito
Joined: 24 Aug 2007
Posts: 5745
Location: Olivella, Catalonia, (Spain)
Expire: 2015-01-07
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 Posted: Sun Oct 21, 2007 6:21 pm Post subject: Fixing Pentax Super Takumar 50mm F1.4 "radiactive" |
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Posted: Sun Oct 21, 2007 6:21 pm Post subject: Fixing Pentax Super Takumar 50mm F1.4 "radiactive" |
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Jesito wrote:
Seen on the net:
http://www.rangefinderforum.com/forums/showthread.php?t=47689
It shows how to cure the yellowish tint, not sure if radiactivity goes away as well or if it's innocuous.
Best regards,
Jes.
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blende8
Joined: 29 Sep 2007
Posts: 260
Location: Bremen, Germany
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Posted: Fri Nov 09, 2007 9:10 am Post subject: |
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Posted: Fri Nov 09, 2007 9:10 am Post subject: |
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blende8 wrote:
Yes, this works.
The point is that over time the glas structure is changing.
There are rumours on the net that this has to do with radioactivity or rare earth elements. But this is not clear.
What is clear though is that it seems that UV light is changing the glas structure back to its original state.
It works better when you put the lens in front of the window glas, if possible, because the glas is blocking UV light.
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Best wishes, Wieland
K-1, K-5IIs
Pentax, mysterium quod absconditum fuit ... |
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vilva
Joined: 04 Mar 2007
Posts: 785
Location: Porvoo/Borgå, Finland
Expire: 2015-05-27
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Posted: Fri Nov 09, 2007 11:34 am Post subject: Re: Fixing Pentax Super Takumar 50mm F1.4 "radiactive&q |
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Posted: Fri Nov 09, 2007 11:34 am Post subject: Re: Fixing Pentax Super Takumar 50mm F1.4 "radiactive&q |
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vilva wrote:
| Jesito wrote: |
| not sure if radiactivity goes away as well or if it's innocuous. |
Just forget the radioactivity, c.f. http://hps.org/publicinformation/ate/q1356.html ,
and if you really want to know, here is the link
http://library.lanl.gov/cgi-bin/getfile?23-01.pdf
An interesting detail: some parts of the lungs of smokers get about 50 times the average annual total, i.e. 16000 mrem (based on 30 cigs a day, if I remember correctly, so one cigarette per day more than doubles the exposure.) Compared to this, these lenses are really negligible.
Veijo |
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