He was one of the pioneers of photomicrography in India. This system was especially valuable in photomacrography (macrophotography) and photomicrography (microphotography). Gerlach was one of the first physicians to use photomicrography for medical research. Wratten filters are also used in photomicrography. It is of particular advantage with long telephoto lenses, macro photography and photomicrography. The publication of photomicrography is given to be the first.