Here today a comparison between the well known Kuribayashi f3.5/35mm lens and the lesser known Steinheil Cassron f3.5/40mm lens. 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. Light source was an UV enhanced Xenon flash. All shots done at f8 and presented on a side-a-side format for easier comparison, left the Cassaron, right the Kuribayashi lens.
[click on image to see a larger one]
Visible light image:
UV image using Baader-U filter (approx. 320-395nm, effective peak approx. 375nm):
UV image using Jupiter-U filter (approx. 280-385nm, effective peak approx. 365nm):
This comparison shows, that the Kuri 35mm is hard to beat, but the Cassaron does quite well for a simple triplet lens, especially reaching quite deep into UV when the Jupiter-U filter is being used. It has 1.9% focus shift, compared to 1.0% the Kuri 35mm has. A quite useful lens and maybe even easier to find than the Kuri.
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