[Leica] Why is the retina curved?

[lrzeitlin at gmail.com (Lawrence Zeitlin)]

Because the plane of sharpest focus of a simple lens is on the surface of a
sphere. Flat film planes are a residue of photography's past when emulsions
were coated on glass plates. It also makes it easier to change film. Curved
film planes are used in both simple cameras and complex telescopes to
provide sharper images. The Minox camera uses a film plane curved in two
directions but requires a concave pressure plate to force the film into the
right shape. Some astrophotographic telescopes coat the emulsion on a curved
sheet of glass configured to lie in the plane of the mirror's sharpest plane
of focus. But as far as the eye is concerned, the high resolution area, the
fovea, is only 3 mm in diameter and the curvature would be very slight. The
retina is curved because it covers the rear of the inside surface of the
eyeball which is itself almost spherical so it can rotate in the eye socket.

I'm sure that's more than you wanted to know.

Larry Z


Le 14 d?c. 09 ? 21:09, simon jessurun a ?crit :



This article made me wonder why is the retina curved and is the film

plane

in a camera flat?


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