Square lens?

-Tom-

-Tom-

Active member
I was just thinking about this, I hope this question doesn't come off too crazy...I'm really just being curious.

So - looking in the back of my GH2, I see a rectangular sensor. Just like in every camera. Yet every single lens are circled. Vignetting, barrel distortion, crop factors...seems like a lot of "space" on sensor is basically unused.

Are there any other reasons that the lenses are circular rather than rectangular other than construction/price? Wouldn't it be logical if the lenses were made in 35mm sizes on their ends, thus throwing maximal amount of light onto the rectangular sensor, regardless of its size?
 
square lens ar really difficult to produc and can be only molded, so exit glass.
but they exist since a long time on these small disposable camera.
i think glass can be molded that way too, but it would be probably very expensive
 
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All the space on the sensor is used. The image from the lens is larger than the sensor. Except if you are using lenses not designed for your camera format by way of an adapter. In that case you might not cover the sensor, a MFT lens will not cover a FF sensor for example.
 
There are other, more minor reasons, but the main reason is because circular lenses, more than any other shape, maximize the ability to produce fast glass that produces sharp images.
 
The physica of optics function in three dimensional space, which is best represented in a circular, spherical shape. A lens doesn't know or care what size or shape sensor is placed behind it. But for the glass to best do its job it must be round. You might better ask why we use rectangular imagers. Throughout history, many portraits were painted on oval or circular canvases. No law that says we could not do this, other than commerce and infrastructure.
 
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