Some block UV, some don't, and some block it part way. It's kind of a crap shoot. You can look at other peoples experiences with each lens and see what you get. Typically the faster lenses, i.e. f/2 or less work well for UV. Most camera sensors have a coating that will block UV, which is generally much more difficult to remove than a hot mirror for IR photography. As far as I know, the only easily converted cameras for UV are the Sigma camera line, like the SD9, SD10, SD14, SD15 because of the layered sensor design. Sigma is the only one that does not use dyes at all for their sensors, unlike Canon, Nikon, Panasonic, etc. Good ol' B/W film does a good job capturing UV. Hope that helps!