A telecine projector comprises a light source 20 illuminating film 29. An objective lens 30 focuses light passing through the film. The light is divided by a prism block 32 and falls onto sensors 34 sensing blue, green, red and infra-red wavelengths, and positioned so that the image size is equal at each sensor.;Light from the source 20 is divided by a dichroic mirror 36 before reaching the film 29. Visible light passes through the mirror 36 and a similarly coated mirror 38. Infra-red light takes the path 37b before being recombined with the visible light by the mirror 38. An aperture stop 40 reduces the diameter of the cone of infra-red light entering the lens 30, thereby reducing the effective aperture of the lens for infra-red light only. The depth of field of the infra-red image is thereby increased, bringing it into focus at the infra-red sensor 34 and compensating for unequal lens performance across the wide spectrum in use.
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