How come the camera is square, the photos are square, but the lens are round?

March 28, 2010 - 7:31 am 6 Comments

Just wondering why? Like shouldn’t it be a square camera lens?

Good question.

First, lenses are naturally round. Making them square would be a lot of work, would ruin the quality, would be bigger, etc.

Second, film is naturally square (rectangular actually). Otherwise you would have a lot of waste space, etc. Plus it’s easier to visualize a square picture instead of a round one. Square film=square picture.

Third, the real question. Why doesn’t having a round lens mess up a square picture in some way? Isn’t this like putting a round peg in a square hole? Why does it even work?

This is the way camera optics work: light comes from the sun, light bulb, etc. and reflects off a point on an object. The reflection scatters in every direction. Cameras capture as much of this scattered light as they possibly can. The physics of a lens is such that when an object is in focus, all the light that strikes the lens gets bent while going through the lens in such a way that it all goes back to a single point on your sensor/film. This is the magic of a lens–it doesn’t matter where the light hits on the lens, it all comes from the same point and goes to the same point (only true while in focus of course). It does this for every point in the image, coming from a point ending up in a point. This is why the shape of the lens, whether it’s square or round, doesn’t matter. The curvature of the lens is critical however.

6 Responses to “How come the camera is square, the photos are square, but the lens are round?”

  1. Katelin Says:

    ha ha good question and why does a round pizza come in a square box?
    References :

  2. The Gland Says:

    In case you’re actually serious:

    because the lense is just to let the light in. The film strip is square so that’s why the pictures are. Digital? Because again, the lense is just to let in the light, not capture a picture.

    and you can take round pictures if you want
    References :

  3. Phi Says:

    Because newspapers, magazines, televisions and movie screens aren’t round, but the human eye iris is.
    References :

  4. asheltonphoto Says:

    Because a square focusing ring would be a real PITA.
    References :

  5. Phillipe Says:

    The round lens makes manual focusing easier. The photos are square because the mask through which the light falls is square, which makes for more efficient use of photo paper.
    References :

  6. bernmeister Says:

    Good question.

    First, lenses are naturally round. Making them square would be a lot of work, would ruin the quality, would be bigger, etc.

    Second, film is naturally square (rectangular actually). Otherwise you would have a lot of waste space, etc. Plus it’s easier to visualize a square picture instead of a round one. Square film=square picture.

    Third, the real question. Why doesn’t having a round lens mess up a square picture in some way? Isn’t this like putting a round peg in a square hole? Why does it even work?

    This is the way camera optics work: light comes from the sun, light bulb, etc. and reflects off a point on an object. The reflection scatters in every direction. Cameras capture as much of this scattered light as they possibly can. The physics of a lens is such that when an object is in focus, all the light that strikes the lens gets bent while going through the lens in such a way that it all goes back to a single point on your sensor/film. This is the magic of a lens–it doesn’t matter where the light hits on the lens, it all comes from the same point and goes to the same point (only true while in focus of course). It does this for every point in the image, coming from a point ending up in a point. This is why the shape of the lens, whether it’s square or round, doesn’t matter. The curvature of the lens is critical however.
    References :

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