Docter Optics replacement high performance lens for 24-36 format image/slide projector. Helical attachment for fine focusing D= 42.5 mm; it is screwed until the image is in focus, after which the lens is fixed with a lateral screw.
With the focal length of 70 mm it is possible to obtain a field angle of 34.5°, while with the focal length of 120 mm a field of 20.5° and of course all the intermediate degrees. Made in Germany.
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