Contrast control with multigrade and variable contrast black & white photographic papers can be achieved in several ways. One of the most widely used ways is through the use multigrade or variable contrast hand filters. Ilford produces twelve multigrade filters that are numbered 00 - 5 in 1/2 steps, with the lowest filter number corresponding to the softest contrast. Filters are available in sets of filters 3-1/2 x 3-1/2" (8.9 x 8.9cm) and 6 x 6" (15.2 x 15.2cm ). They can be used above or below the lens and can be cut to fit the enlarger filter drawer. Multigrade filters are very easy to use: no complicated calculations are needed when changing from one filter to another. The exposure time for filters 00 - 31/2 is the same; that for filters 4 - 5 is double.
