The Hitech 6 x 6" #38 Light Blue Filter is a general contrast filter, primarily for use with black and white film. This light blue filter helps to correct the tendency of reds reproducing too lightly under incandescent lighting. This filter absorbs much of the red tone in the image as well as providing UV attenuation.
There is a 1.5x filter factor with this filter, requiring an increase of 0.6 stop for normal exposure. This filter measures 6 x 6" / 152.4 x 152.4mm and is constructed from specially dyed CR-39 resin.