Light source unit assembly for photographic enlarger

In an optical element for use in a photographic enlarger positioned on the optical axis of a light source between the light source and a negative for diffusing the light from the light source and illuminating the negative, a light source unit assembly comprising a frame having a diffusing tube at least in its interior and a partition provided in the frame and dividing the interior of the diffusing tube into a first diffusing chamber and a second diffusing chamber;

• the first diffusing chamber having a first light diffusing surface on the partition, a first light passing aperture positionable on the optical axis of the light source and opposed to the first diffusing surface, a first diffusing filter disposed across the path of light reflected from the first diffusing surface and a condenser positioned on the optical axis of the first diffusing filter and spaced apart from the filter to provide a first optical system;
• the second diffusing chamber having a second light diffusing surface on the partition, a second light passing aperture positionable on the optical axis of the light source and opposed to the second diffusing surface and a second diffusing filter disposed across the path of light reflected from the second diffusing surface;
• the first and second optical systems being alternatively positionable on the optical axis of the light source between the light source and the negative.