Why is a lens round and the pictures square?

Question

The lenses used to take pictures and video images are always round, yet all the pictures and imagery comes out square... why???

Answer 1

Basically at the back of the camera is something senseitive to capture the image. In the old days it used to be film, now it's a light sensitive chip.

The lens focusses the image on to this rectangular sensor. The picture focussed on to the photocell or film are slightly larger than they need to be and round. The edges of the image go beyond the sensitive area abd are cut off. If this did not happen you would waste part of the film or photocell.

It would be difficult to manufacture a square lens that focused exactly onto the square photo cell. Also it would be difficult to store round images both digitally or on paper.

Answer 2

There is a very easy answer to this question, it is easier and therefore cheaper to make a square lens, no other reason.

Basic optics can prove this, but you can prove it easily (and cheaply if you have a digital camera).

Cut out a square, preferably on black paper, a little smaller than the camera lens, then take a photograph with the card right up against the lens centrally. Be careful you don't damage the lens.

Answer 3

Rather than extend the lens to focus and zoom by sliding it, it is more controllable to turn it. As you rotate the lens it has to give the same picture area, a round lens is the only way to do this.

Answer 4

Because they are electronically cropped. In the old days the negative was square and then rectangular thus the photograph came out "square". Imagine looking for a photo album to fit round pictures???

Answer 5

Lenses were copied from the human eye.

Besides, if lenses were square we wouldn't have the term "spherical aberration" to ponder.

Answer 6

Giid question. At first it seems like a real quandary until you think about it and then it does make sense. But I agree that it does seem a strange thing at first look

Answer 7

Because the sensor/film is square.