Today a spectrometric test using that previously mentioned Petri Kuribayashi f3.5/35mm lens, compared to the W. Acall f3.5/35mm lens in Leica Thread Mount (LTM), as a proof that both actually have a very different lens transmission, especially in UV.
[click on image to see a larger one]
The Kuribayashi 35mm reaches much deeper into UV, even a bit below 320nm and shows a rather high UV at 365nm transmission of over 75%. However the similar looking W. Acall 35mm seems to be a very different beast, as it has at 365nm only approx 5% UV transmission, so basically none useful at all!
I have written about that lens before HERE
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