Matt Laur , Mar 02, 2009; 10:23 a.m.
If you really need (for creative purposes) to have that lens wide open in brighter light - and I do understand the urge! - then what you want is an ND (neutral density) filter. Essentially, sunglasses for your lense. You can get them several stops dark, if need be. Of course, it's another layer of glass over your fine lens... so don't scrimp. Get a good one from B+W or Hoya.