Abstract: A compact and light weight radiographic collimator including two pairs of radiation absorbent shutters connected together by a parallelogram linkage which provides a nested arrangement when the shutters are in their full open position yet provides an aligned relationship when fully closed. An off-focal vane construction in which the vanes are moved reciprocally is also disclosed.The shutters and vanes may be either manually or automatically adjusted. Manual adjustment is automatically limited to the maximum safe open position.A collimator adjusting drive train using constantly meshing gearing and a slip clutch is employed. A series of filter plates of varying thicknesses are provided. The operator can select the filtration desired by positioning each filter plate in either its filtering or nonfiltering position and then insert the stack of plates into a slot. A sensor provides an indication of when the filter assembly is positioned in the collimator.