Friday, October 12, 2012

Old enlarger lens: reflected UV ultraviolet photography

I was digging through boxes, when some older, but new in box  f4.5/50mm enlarger lens fell into my hands. Well, I was curious to see how it would perform in UV, so I took a few shots in the Hermannshof park with it, using my "work horse" UV filter that never let me alone, the Baader-U filter. How nice that this lens has a 40.5mm  filter thread, as not all enlarger lenses have that. A simple short M42 focusing helicoid served as a focusing aid and as it has a Leica thread mount (M39), so simple M39-M42 ring was all needed to make it fit. All shots were done at f8 in evening last sunlight with not much UV left to use.

[click on image to see a larger one]

Rudbeckia hirta, wild form from Illinois:


same, but closer:


Rudbeckia fulgida:
 

Quite impressive performance for a most likely simple Cooke triplet 3e/3g lens. Oh and I forgot to mention, is has no (or barely any) focus shift. Here is its transmission graph versus my usual reference lenses.

 

More research and testing needs to be done, but it could form the basis of a comparably cheap UV photography system; we'll see...

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