Are glass filters superfluous since digital photography came along? By no means. The high-grade, coated neutral-density filter by B+W, for example, allows the creative possibilities of a wide open Summilux or Noctilux to be used fully, even in ambient light situations. And for the M Monochrom, the Leica colour filters are as essential
for the regulation of grey values through the targeted filtering of the components of visible light, as they always were in the case of black and white photography. Infra-red filters, on the other hand, ensure amazing effects; like with the the Leica M8, which is particularly susceptible to infra-red light.