In a message dated 9/30/2006 10:18:43 P.M. Eastern Daylight Time, sstoney@xxxxxxx writes: No, if the filter factor is 2 x you would open 1.41 stop not 1, !!!! This is very confusing. Why do they call the filter factor 2 if it's really 1.4? --shannon Ahhhhh, I don't know. Maybe Ralph, Richard or someone knows. Bruce Osgood Camclicker @ aol.com Brooklyn, NY.