Photometric unit for photographic projector-printer assembly

摘要

The present invention provides a photometric unit designed for a photographic projector-printer assembly, which does not require a movable portion and is thus simple in its structure and eliminates any time lag in focal length change. The photometric unit 20 is diagonally offset with respect to the projection-side optical axis and has two area sensors 9 and 10 mounted in parallel with each other on a common substrate plate 8 and two image-formation lenses 11 and 12 having different focal lengths, which are located in operative association with the two area sensors. The optical axis a of one image-formation lens 11 having a longer focal length is positioned such that it intersects the optical axis of the projection optical path at a point O on the negative film, whereby a negative film image formed on either one of said area sensors depending upon the size of the image on said negative film is photoelectrically converted for photometry measurement.