If Camera Lenses are Round, Why are the Pictures Rectangular?

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Its a bright and sunny day, most probably you and your friends are heading out to the sea and possibly one among your friends is a photographer who goes out taking a lot of pictures of you and the nature. Suddenly out of the bloom from the crowd, comes this kid and asks them,

“If the camera lenses are round, how come the pictures are rectangular?” 

Now the real fun begins, none of the grown up adults know or probably few of us know about it but no one among the gang of friends knew about this, probably not even the photographer. So for all those of you I thought I will explain you about the technology behind it.

Its quite obvious from the structure of a camera that the lenses are round and they take beautiful pictures for you. But it is not the lens that develop these pictures inside a camera, there is a component called the Image Sensor in modern cameras that is connected  in conjunction with the lens. In the older cameras it was the FILM which did the job for you.

There can also be rectangular lens right? But when the early camera makers thought about this one of the camera pioneers figured out that though lenses can be made in any shape only round lenses produced good image on the image sensor.

so how does this take place?

As light bounces off of an object you’re photographing, that light enters through the camera’s lens. The job of the lens is to bend that light and focus it onto the film or the image sensor. This is the basic physics with which the cameras work.

Now coming back to the topic, the next question probably running in your mind might be why are the films rectangular?

The answer to this question is again very obvious and common sense. Imagine a photograph which is round and you want to frame it, if you take it to a shop for framing it then probably he will look at you up and down for five minutes and suggests you to leave the shop and look for some other shop to frame it. It is for this simple reason that the films were rectangular and even the sensors now.

There is also another scientific reason behind the rectangular sensors.  A round camera lens does produce a round image inside the camera. However, the outer edges of the round image will have more distortions, sometimes called aberrations, than the parts of the image closer to the center. This is because light must be bent more to reach the outer edges of the circular image.

To correct for these aberrations and end up with the best image possible, the rectangular sensor crops out the outer edges of the circular image from the lens. In other words, it only keeps the best part of the image from the lens. This gives you better photographs than you would get if you kept the entire circular image from the lens.

Hope this helps, if you have more queries just hit me a mail or comment and lets start our discussion from there.



Manigandan Siva.