Round lens, Square picture. Why?

My young son asked me why the end of the camera (lens) is round but the picture is always square (I explained oblong)

I had no answer for him. And as stupid as the question seems even as I type it. I still have no answer.

So ask the experts time

There is no reason why the 'picture' can't be any shape (square, oblong, circular). You are effectively cropping the image projected onto the film/sensor.

this was much discussed here if you're interested:

http://photo.net …ch-msg?msg_id=0044WO&tag=

Andy

The reason it's not circular is because film is easier to make in strips than a bunch of small circles. I would also assume making a bunch of circular frames wouldn't look as well around the house
not to mention the square film is actually cropping the orginal circular image.

Smart kid!

Livinthalife wrote in post #2161781
The reason it's not circular is because film is easier to make in strips than a bunch of small circles. I would also assume making a bunch of circular frames wouldn't look as well around the house
not to mention the square film is actually cropping the orginal circular image.

Smart kid!

The exact same reasoning goes for digital sensors. They are all laid out on a wafer in neat rows and cutting in straight lines is much easier than cutting out a circular chip.

Now this begs the next question. All chips are rectangular/square so why are wafers round?

put a fisheye on a ff or 1.3x cam, you'll get a round image it just happens to have a black area around it

gjl711 wrote in post #2163795
... Now this begs the next question. All chips are rectangular/square so why are wafers round?

It has to do with the wafer manufacturing process... the wafers are typically made by thinly slicing single crystal ingots of semiconductor materials (a.k.a. boules) with a diamond saw. The boules themselves are long cylindrical rods, due to the crystal growing process. Hence, the end result is round flat wafers.

I told my kid that photos are square, because if they were round they would just roll out of the camera. He is five now, and I think he is starting to suspect something.

mjgravina wrote in post #2165909
I told my kid that photos are square, because if they were round they would just roll out of the camera. He is five now, and I think he is starting to suspect something.

This is by far the best answer yet. Scratch my earlier answer. This is the real reason.

Livinthalife wrote in post #2161781
I would also assume making a bunch of circular frames wouldn't look as well around the house

I guess that depends on the house. I would imagine a bunch of round frames would fit in nicely with house boat decor.

Now Seriously, Accrington, your son deserves a lot of credit for the question. It takes a very creative and inquisitive mind to analyze a system, find discrepancies, and then voice the issue.

I assume that the paper they had for printing was rectangular from the very first photos, and it was easier to handle throughout all the chemical processes (Silver coating and etc). I know the first pin-hole cameras were square. (What if nowadays we constructed a circular pin-hole camera?).

Your kid brings a really good experimental WHAT IF question. Imagine a round Sensor, capturing much more than the simple tiny sensors we currently use. Would it make a difference in the amount included on the photograph? Absolutely !... I dont know how old your son is, but this is a great topic to embark on some father-son quality lab time, trying to figure out how it would work, and why things are the way they are. He will definitely understand better the basic concepts of photography.

I just didn't want to leave my comments with a joke, because it is a very valid question.

Cheers,

Regardless of how "young" your son is, he obviously has good spatial thinking skills. Most people will never think of that question. I'm going to pull out my crystal ball here....it gives me answers in the shape of a cube.....and I'll say your son will be talented at physics or mechanical engineering someday. My crystal ball isn't perfect. It doesn't give me the complete picture. Just crops it into a cube.