NikonGear'23
Gear Talk => Lens Talk => Topic started by: Dr Klaus Schmitt on December 27, 2018, 15:54:35
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A while ago, on my search for affordable lenses for reflected UV photography, I discovered in an older UV-VIS spectrometer system some seemingly useful Quartz Fluoride Lens system (QFC) of approximately f3.2 / 81mm. It had to be modified to convince it to work with a camera, and also a variable aperture had to be added, but I succeeded finally to get it to work on a mft camera system.
So today a comparision between my "work horse" UV-Nikkor f4.5/105mm (top) and this QFC f3.2/81mm (botttom):
(https://a4.pbase.com/g10/08/747708/2/168597486.wPW2DoCn.jpg)
(https://a4.pbase.com/g10/08/747708/2/168597481.cVnG6kUL.jpg)
Both images are a Quadriptych of VIS, reflected UV, sim. Butterfly and Bee vision (left to right, top to bottom)
Both lenses differ in focal length, 105mm for the UV-Nikkor vs 81mm for the Quartz Fluoride Condensor lens, and lens speed f4.5 vs f3.2 but other than that they are quite comparable: there is hardly any focus shift, just sharpness and contrast is higher with the rather expensive UV-Nikkor lens compared to the Quartz Fluoride Condensor lens, quite as expected. Other than that this old lens does very well, but it only covers mft sensor format, possibly APS-C (with another modification).
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It is always difficult to spot the differences between the visible and the ultraviolet image. Hence a few years ago I have developed a method to show a differential image VIS-UV which tuned out in such a way that I call those "psychedelic" due to it colors...
But see for yourself, first the normal visible image, then the UV image, then the differential...
(https://a4.pbase.com/g10/08/747708/2/168597482.VS5L8Sya.jpg)
(https://a4.pbase.com/g10/08/747708/2/168597483.LpI7Cnoy.jpg)
(https://a4.pbase.com/g10/08/747708/2/168604484.u9JfXgrD.jpg)
So those light blue areas denote high UV reflection...but I'm sure you saw that already ;-)