Abstract: A photographic finder camera adapted to use interchangeable photographic lens objectives and having a photoelectric detector system for measuring the light flux passing through the photographic lens objective employed in each case. At least one movably mounted optical component is disposed in the camera housing which component directs at least a part of the light flux coming from the object to be measured and passing through the lens objective to the photoelectric detector system. Control means are provided to selectively move this optical component into the measurement position in the beam path of the camera lens objective and depending on the actuation of the shutter, to transfer the optical component into a non-use position.

Abstract: Disclosed is a device for the detection of back-scattered electrons emitted by a specimen in an electron microscope, comprising a converter for converting back-scattered electrons emitted by the specimen into secondary electrons, which converter includes a surface layer of a crystalline material having a low atomic number and a low electrical conductivity, preferably magnesium oxide; and a detector for detecting secondary electrons emitted by the converter. Also disclosed is an improved electron microscope embodying this detection device.