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Unusual optics of the Polaroid SX-70 Land camera.

The unique optical system of the folding single-lens-reflex viewfinder used in the Polaroid SX-70 Land camera has required novel approaches to design and manufacture. The camera uses an unusual short-barrel taking lens with front-element focus, two plane mirrors, an eccentric reflective Fresnel focus screen, an aspheric aperture element, an aspheric concave mirror, and an aspheric eye lens. All the viewing components are tilted or decentered, and two aspheres are not figures of revolution. Beginning with J. G. Baker's computer design, special technology has been needed for producing millions of replicas of this system and controlling their quality.