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Asahi Opt. Co. Super-Multi-Coated Takumar 1:3.5 / 28

4 replies to this topic

#1 Herman1705

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Posted 22 October 2016 - 23:12

Searched for a thread in the forum but could not find one on the Asahi Opt. Co. Super-Multi-Coated Takumar 1:3.5 / 28. Recently got this lens (back); I think I used it in the late 80's on a Pentax during a trip to Paris; moved 2 times in the meantime and knew that it had to be somewhere.

Some data:
Attached Image: Takumar-28mm_.jpg

(Have to clean the front :) )
Attached Image: 20161022-DSC_8433.jpg

Attached Image: 20161022-DSC_8436.jpg

Attached Image: 20161022-DSC_8437.jpg

Blacklight lit ColorChecker; filters: stacked U340 (2mm) and BG40 (2mm); 45 s exposure:
Attached Image: 20161022-_DSC6643.jpg

Blacklight lit Strelizia; filters: stacked U340 (2mm) and BG40 (2mm); 30 s exposure:
Attached Image: 20161020-_DSC6587-2.jpg

I still have to do some fieldwork with this lens.
The images of the plant and the colorchecker show UV transmission. Anything known about the spectral UV range of this lens?


Herman

#2 nfoto

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Posted 23 October 2016 - 00:20

I'd be surprised if it goes any deeper than 380 nm or thereabouts. However, only field experience can indicate if the lens is useful for some kind of UV work.
Bjørn Rørslett

#3 OlDoinyo

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Posted 23 October 2016 - 05:42

At least this is not one of the thoriated lenses.

You could do a pinhole test on the lens and compare the result to that using optics of more known properties (if you have them.)

#4 Andrea B.

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Posted 23 October 2016 - 17:13

That is a very long exposure time which would possibly indicate that there is some blockage of UV.
Andrea G. Blum
Often found hanging out with flowers & bees.

#5 Reed F. Curry

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Posted 23 October 2016 - 18:33

I have always been disappointed with the Takumars. Even those without Thorium-laced glass seem to have a yellow cast to the glass that inhibits UV transmission. Of course, seven groups doesn't help either; that is eight glass/air interfaces.
Best regards,
Reed
http://www.uvroptics.com