Tuesday, March 12, 2013

35mm enlarger lens for reflected UV photography

Today again about a simple, but UV capable enlarger lens of 35mm focal length. I have done a similar enlarger lens comparison for a 100mm lens here and here and a comparison for 50mm lenses previously here. I'm using a yellow/red Phalaenopsis flower for that and my "work horse" UV filter, the Baader-U filter plus the deeper reaching Jupiter-U filter. The maker of that simple triplet enlarger lens will be revealed here later - or simply contact me about it. Light source was an UV enhanced Xenon flash. All shots were done at f8 and are presented in a side-a-side format for easier comparison.

[click on image to see a larger one]

Images showing on the left a visible light image and on the right using the Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):
 

UV images using shown on the left the Baader-U filter (approx. 320-395nm, effective peak approx. 375nm) and on the right my Jupiter-U filter (approx. 280-385nm, effective peak approx. 365nm):
 

UV detail images using shown on the left the Baader-U filter (approx. 320-395nm, effective peak approx. 375nm) and on the right my Jupiter-U filter (approx. 280-385nm, effective peak approx. 365nm):
 

Transmission graph:
 

Well, this little lens performs acceptably well, seemingly has quite a high UV transmission of about 80% and quite a deep reach into the UV region to about 320nm (white line), compared to my new standard 35mm lens (green line), the Kuribayashi 35mm. I also tested a rebadged version under a different moniker (pink line) which seems to perform about identical.


Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos