eli5 Why are camera lenses round when all media we view is square or rectangle
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Electronic sensors and chips are easy to make rectangular. In particular, a cmos or digital camera sensor is just an x by y (your resolution) grid of little light detectors. You can make em round, but you’re just wasting pixels and board/chip space.
Meanwhile lenses are easy to make round and super hard to make square – actually they just make a bigger round one and grind it into a square shape. But essentially whats going on in your cell phone is the lens is right shaped and sized to transmit and focus light into a circle into which our rectangular sensor exactly fits. So technically we’re wasting a bit of the light that comes through that lens. Im not an optics guy but Im willing to bet if you made a rectangular lens that exactly covered just the sensor, you’d have a lot of weird distortion effects in the corner you’d have to compensate for, depending on how you centered the center of the original round lens when you ground it rectangular. And you tend to get more distortion effects towards the edge of any lens anyway**, so if you just use a larger lens, the distorted bits at the edge are just ignored because you have no sensor there.
**at least in the lenses that my company’s product use anyways.
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