Herman1705 Posted October 22, 2016 Share Posted October 22, 2016 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: (Have to clean the front ) Blacklight lit ColorChecker; filters: stacked U340 (2mm) and BG40 (2mm); 45 s exposure: Blacklight lit Strelizia; filters: stacked U340 (2mm) and BG40 (2mm); 30 s exposure: 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 Link to comment
nfoto Posted October 23, 2016 Share Posted October 23, 2016 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. Link to comment
OlDoinyo Posted October 23, 2016 Share Posted October 23, 2016 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.) Link to comment
Andrea B. Posted October 23, 2016 Share Posted October 23, 2016 That is a very long exposure time which would possibly indicate that there is some blockage of UV. Link to comment
rfcurry Posted October 23, 2016 Share Posted October 23, 2016 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. Link to comment
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