Stupid question of the year ......

northernstar074

northernstar074

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Anthony
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Right, I got asked this the other day and I didn't knwo what the answer was so here goes ....

Almost everything to do with cameras is rectangle ... prints, viewfinder, lcd screen on the back .... so why is the lens round ?
 
quick simple answer

it's because the aperture inside the lens is round..
 
Summat to do with light coming in from 360 degrees, innit?

If you had a rectanglier lens you'd get completely weird light and dark patches (though in the same place each time, I would imagine).
 
Noob answer and so read with caution... It is so the light is refracted to reach the smaller sensor/film as evenly as possible. It's like, why aren't your eyes square? It is to simulate how the eye behaves I believe. I am just a noob and could be completely wrong though.
 
The questions the wrong way round... the fiddly bits inside the camera are round.. the lens is round..(google for more in depth re fiddly bits). the actual picture you take is round I believe but that could be wrong.. hmm no I think its right... so the question should be why are the pics produced rectangular .. and if i remember right its all down to printing, ease of use and price.... imagine a world with round photos and round photo frames :)
 
KIPAX said:
The questions the wrong way round... the fiddly bits inside the camera are round.. the lens is round..(google for more in depth re fiddly bits). the actual picture you take is round I believe but that could be wrong.. hmm no I think its right... so the question should be why are the pics produced rectangular .. and if i remember right its all down to printing, ease of use and price.... imagine a world with round photos and round photo frames :)
Click to expand...

i like the idea of round pictures :)
 
The image itself IS round

But the picture you take is a rectangular crop, it's not round at all

Any other shaped lens would give huge/ridiculous distortion problems as the rays of light are refracted through the lens - it just wouldn't work

DD
 
could be rather difficult to make a rectangular piece of glass that allows zoom, etc without distortion.
 
that question and answer just made my day.
bring on thursday night pub time and my fasinating new fact :woot:
 
Manufacturing costs of a rectangular lens would be prohibitive. It's simpler and cheaper to start making a lens from a circular blank rather than having to cut a rectangle. It then has to be held while being ground - again simpler with a circle. You could cut the finished lens in to a rectangle, but that would be pointless.

Also, early lens attachments were screw threads, or in the case of large format cameras, mounted on boards as required. This immediately causes a problem getting the edges of a rectangular lens in line with the edges of the film.

Then there is the problem of aperture irises. Try making a working rectangular one. Likewise a shutter for a lens needing one built in to it.

And having come across many older zoom lenses in which the front lens element rotates on zooming, I think non-rotating front elements are a relatively recent feature.

So, cost and practicality are the answers.
 
mrE has it!

also, there used to be "round" film cameras. The film used to be rectangular, but only a circle was exposed. some early Kodak cameras had this, see the original "point and shoot" (aka Box Brownie)
 
KIPAX said:
... so the question should be why are the pics produced rectangular .. and if i remember right its all down to printing, ease of use and price.... imagine a world with round photos and round photo frames :)
Click to expand...

Even though you have round eyes, the view you have of the world is more rectangular due to you having two eyes. Close one eye and you have a fairly circular view, depending on the size of your nose. Open the other one and it becomes more rectangular, with rounded corners. Circular photos do not give a natural view.
 
AleksanderLoesch said:
mrE has it!

also, there used to be "round" film cameras. The film used to be rectangular, but only a circle was exposed. some early Kodak cameras had this, see the original "point and shoot" (aka Box Brownie)
Click to expand...

Indeed - the only justification for vignette!
 
A lens always throws a round image whatever its shape.

It is to do with the curvature of its surfaces more than its outline.

Some cameras do have rectangular masked lenses, and view finders mostly do.

It is far easier and accurate to make lenses with round mounts and far easier to construct focus mounts, Zooms, apertures etc..

The earliest cameras took round pictures and they were not trimmed as people did not want to "waste" any of the image.

Modern lenses still make round image but apart from Fish eye lenses we mask them rectangular. On large technical cameras we take advantage of the larger image circle to give "movements" to the Back and lenses standards of the camera.
 
The lens throws a round circle of light but the actual sensor is rectangular. Film is rectangular purely for storage purposes and digital sensors follow this norm. Vignetting is a perfect example of how the circular light is put onto the rectangular sensor.
Good question though, love the thought process.:thumbs:
 
Take two fingers at 12o'clock and trace the outline of your visual field from top to bottom, rectangle? I don't think so...
 
Hyster said:
Take two fingers at 12o'clock and trace the outline of your visual field from top to bottom, rectangle? I don't think so...
Click to expand...

I don't believe I said anything about the outline of our visual field when referring to a vaguely rectangular field of view. You don't walk around rolling your eyes round to take in the maximum field of vision do you? You see two overlapping circles which is more akin to a rectangle with well rounded corners than a circle.
 
Hello
I have a Rolliflex book from the 1950’s which suggests ‘photos should be square (like those from a 6X6 Rolliflex) as it makes the best use of the circle of light produced from a lens.

Camera lenses developed from pinhole camera obscures. The pinhole produces a sharper image the rounder and smaller it is. To make the image brighter make the hole bigger but sharpness falls off so you put a glass lens in it to compensate so you get round lenses.
Photos, I would suggest, are square or rectangular because paintings, tapestries etc are traditionally this shape. So if you were inventing a new picture process it may not even occur to you to make it any other shape than “picture shape”.

These are not facts, just my musings for what they are worth.

P.S. Not a stupid question!
 
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