Why Are Lenses Circular if Sensors Are Rectangular?

4 years 8 months ago #654855 by Benny13
I'm not sure where to even ask this. But I was just thinking, lens is round, yet when you take lens off camera, you are looking at rectangle sensor.  Why don't these match?  I can't imaging a rectangle lens, but not sure why we don't have a circular sensor.  


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4 years 8 months ago #654869 by Nikon Shooter
Right from the beginning — around the late 16th century,
lenses were made circular and that was a side effect of
the circular motions to achieve proper polishing. Cars, like
lenses, are better polished with circular motions.

A square lens can be made but sure consequences, optical-
ly speaking, are the very irregular projection, the uneven light
transmission, and the worst vignetting one could imagine not
to mention all kind of aberrations.

The sensor is not relevant — it could have any shape — as
long as the projection circle easily covers all it surface.

Light is free… capturing it is not!
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4 years 8 months ago #654884 by garyrhook
Aside from the mechanics of grinding and polishing a lens, per the above, note that a circular lens has no orientation. One less issue to worry about for manufacturing, as well as mounting the lens.

Then think about the aperture blades. They're still going to need to be round. What's the point of rectangular glass when other parts have to be round?

In other words, the lens is circular for more reasons than just the glass, and the glass is circular because of many reasons.


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4 years 8 months ago #655000 by Marin Chi
Can you imagine a round camera?  OMG a bubble.  


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