Saw this on a shower thoughts post, and now I need to know. The internet has just given me more and more confusing answers so far, so I’m in need of a 1st grade lecture.
In: Technology
Cameras work by shining light on something that changes color forever when the light hits it. While the lens may be a circle, the thing the light hits is a rectangle.
When cameras first became popular, the thing the light hit was a roll of film. It was essentially one long, thin sheet, rolled up onto a spool. The camera would cover all but a small section of the roll of film, and allow the light to hit that.
Because of the way it was shaped, the piece left uncovered was a rectangle, because you could fit more rectangles on a roll of film, which fit more pictures, so it cost less per roll of film.
Given the laws of optics it’s much easier to design a circular lens than a rectangular one. Both are possible, but rectangular lenses need to be cut from from circular ones so more cost and more error. So it’s about manufacturing. However image detection is accomplished with a rectangular sensor, it’s traditionally made that way because it’s easier to make, package, and rectangular images are the norm. So it doesn’t matter that the image falling on the detector is circular, because the detector will only detect part of it, a rectangular part.
Edit: for more details, please see https://photo.stackexchange.com/questions/40908/why-are-lenses-always-round-in-shape
And English
Telescopes and microscopes and binoculars are circular too. It’s much easier to grind a good circular lens. Someone else can ELI5 lens optics.
As for rectangles, it’s how we like to view the world. It simulates the landscape horizon our eyes evolved to see. (Apparently Hobbits evolved in the berths of ships)
We have round eyes (pupil, lens, cornea, etc) and rectangular TV’s for basically the same reasons.
In a camera there is something called aperture. By definition, it is the hole or opening where the light enters. This hole/opening is made bigger and smaller by certain controls on your camera. Its what’s used to make a well-balanced photo. Simply though, it’s how a camera receives light. Think of it as the iris of your eye.
When we were first “discovering” and creating cameras, it was found that a circular lens did this job most efficiently, and engineering-wise, it was found to be easier as well (which makes sense, because irises are very efficient).
So why rectangular? Well one is very obvious. Before cameras, in what shape are the vast majority of all paintings? Squares and rectangles. To put on walls, to make canvasses for, to make frames for — these were the easiest shapes.
Secondly, when the camera was being developed, its pictures were made into film. Film came out in strips, so why waste empty space by having circles on this film?
So nowadays, after the initial development of the camera and since we don’t use film anymore or worry about the means to bend wood into wooden frames, why do we still use a rectangle (for the most part)? Because now, it still just makes better pictures. This is because the camera does produce a circular photo at first, but the camera’s rectangular sensor cuts out the outer edges. (In my own personal opinion this is why photos look way different, depth-wise, than in person).
It automatically cuts these edges out because the light has to bend more in order to reach that far. The lights bends so much it leaves behind distortions (or also called aberrations). So essentially, its an automatic edit and focus to made a clearer and proportionate photograph (although smaller).
And lastly, as a another personal note, I think they’re also still rectangle now because pretty much all screens (camera screens, laptop screens, phone screens) are all rectangular too. It just makes sense.
Source: took some classes and took some pics, but please anyone with any edits please let me know 🙂
edit: grammar and also hoping I explained it well OP, if you have any more questions please ask
So what shape is the thing behind the lens of my phone?
The image is captured by the camera’s sensor – which is rectangular. While the lens itself is circular, it is only needed to focus and modify the light – you could also take pictures without a lens (albeit the images will just be a blurry….something.)
The sensor behind it is rectangular. And it’s rectangular because that’s what most people want photos to be. After all you’re usually going to print photos on rectangular pieces of paper, or display them on rectangular screens.
Latest Answers