Old 105mm + 75mm Helioplan enlarger lenses for reflected ultraviolet photography

Today about some older, quite capable UV transmitting Helioplan enlarger lenses. I'm using a Gazania rigens flower for that test as well as my "work horse" UV filter, the Baader-U filter. Lenses used were older 75mm and 105mm Helioplan enlarger lenses of dialyte construction. Light source was Xenon light. All shots were done at f11.

[click on image to see a larger one]

Diptych image using 75mm lens, Visual and reflected UV using Baader-U filter (approx. 320-395nm, peak approx. 350nm):
 

Diptych image using 105mm lens, Visual and reflected UV using Baader-U filter (approx. 320-395nm, peak approx. 350nm):
 

Diptych image 75mm vs. 105mm lens, both reflected UV using Baader-U filter:
 

The comparison images clearly show that the 75mm has an edge over the 105mm lens in terms of UV tramsission, but also in terms of sharpness. Both lenses are nevertheless quite capable, despite their 50++ years of age.

P.S.: The visual images were not re-adjusted in focus, to show the small focus shift between VIS and UV.

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