Video tends to have a larger depth of field than its film cousins so that if one uses an ND filter, you can open up the lens and decrease the depth of field, and defocus the background.
Many believe that this helps to make something shot in video look like film. I don't agree with this idea in that if you look at a film like Citizen Kane, which Orsen Wells is well known to have had a huge depth of field, it still looks like film. It doesn't look like video. So personally, I believe depth of field has nothing to do with making a video look like film or vice versa.
On to your second question, what are you trying to achieve with trying to figure out how CTB affects wattage? They really have nothing to do with each other. But if I were to hazard a guess, if full blue cuts down light by two stops, then it might be comparable to a 125 watt size bulb.
And yes you can use a lens wipe on a filter.
PS Soory for the some duplication. I started writing this before laurants was up.
Edited by heel_e, 17 July 2005 - 10:23 PM.