Projection Lens Requirements

How large will my projected image be?

The formula for calculating the size of a projected image, used in this calculator, is:

Projected Image Size = (Object Size*((Distance to Screen*12)-Focal Length of Lens)/Focal Length of Lens)/12

Suppose you are planning on projecting 35mm slides of your art onto a 10' x 14' screen. The distance from the lens mounted on your slide projector to the projection screen will be about 30 feet. The aperture on a 35mm slide is 1.41" x .944". In order to calculate what size the projected image will be you would enter 3, 30, and 1.41 into the calculator and then press "Solve". The result will be 13.98 feet.

Enter the focal length, in inches.
Enter the lens to the screen distance, in feet.
Enter the object size, in inches
The projected Image size in decimal feet.
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