969,811. Photomicrography; exposure control. ERNST LEITZ G.m.b. H. June 22, 1962 [June 28, 1961], No. 24076/62. Heading G2A. A light beam intensity control device for use in photomicrography comprises a device of variable light absorption arranged for insertion in a light path of a microscope by means controlled by a light sensitive member provided for measuring the intensity of the light beam after it has passed through the object so that the intensity of the light beam be adjusted for the exposure of photographic material of given sensitivity for a given exposure time. In the embodiment shown, light from a source ,1 passes through an object 5 which is photographed on a photosensitive surface 13 through a shutter 14. The shutter can be set to one of two speeds, one comparatively short the other comparatively long. For each speed the intensity of the light beam falling on surface 13 is varied by increase of a movable grey wedge or polarizing means controlled by a servomotor 19 and a control device 18. The device 18 is in turn controlled by a light sensitive element 17 on to which the light beam may be directed by means of a pivoted mirror 15. The object may be viewed by means of a half silvered mirror 7, reticule 9 and eye-piece 8.