[click on image to see a larger one]
Visible light image for comparison:

1) Quartz Fluorite lens: "standard" UV image using Baader-U filter:

2) Enlarger lens: "standard" UV image using Baader-U filter:

UV - VIS differential:

It gets pretty obvious that this very affordable D.O. Industries enlarger lens reaches quite close to the quartz fluorite lens, yet can't quite beat it in terms of sharpness + contrast. But it is astonishingly close. Also its focus shift is relatively small, as the differential image clearly shows. Quite a nice lens!
I have written about that enlarger 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