So today about UV photography using this lens, executed using one of my last Rudbeckia fulgida flowers. Shots were done using the UV Baader-U and XNUV filter as well as the bee vision simulating XB4 filter. My modified Xenon flash was used as a light source. Oh, and no focus correction was done!
[click on image to see a larger one]
Visual image using UV/IR Cut filter:

Simulated Bee vision using XBV4 filter:

UV image using XNUV filter:

UV image using Baader-U filter (with usual whitebalance):

UV image using Baader-U filter (with special whitebalance to resemble a quartz fluorite lens):

Well, the UV transmission is not that great, as may be seen from the colors of the second to last image, but still quite useful and especially sharp. So, maybe you you understand why I was so surprised again about the performance of that lens - no wonder its larger brothers (8/110mm and 5.6/55mm) were used in cold war as a aerial imaging lenses. And btw. if you like to see how amazingly this lens performs in the visual, have a look HERE from 2011 and HERE from this year.
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