just turn up the asa dial, shoot right through that cap!
+1!! I am curious, though, how high should one set the ISO in order to shoot through the lens cap, and obtain a good contrast black and white negative? I have always preferred taking the easy path and just removing (and leaving in my camera bag) the lens cap. However, if one can, in fact, shoot through, the cap, then I (and countless other rangefinder shooters) wouldn't have to be concerned about losing lens caps (and those damned Leica caps are often north of $30 per!).