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3:2 feels more suited for the modern way of watching photos, like on a laptop or any form och wider screen model. Why do they keep making the 4:3 ratio?

What historic reasons are there for common aspect ratios? - This is an excellent thread, and I have both read and upvoted it since it takes the historical part behind this in to exceptional depth.

Why do they keep using this 4:3 ratio? Is there something blocking compact cameras from using 3:2, like their size?

marked as duplicate by mattdm, Philip Kendall, scottbb, Michael Clark, Caleb Dec 23 '16 at 7:05

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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    The above covers how we got here. As for the future... that seems entirely speculative. – mattdm Dec 22 '16 at 10:39
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    maybe we should be grateful for 4:3 as it gives more sensor area for a given image circle diameter and those sensors are already quite small... – szulat Dec 22 '16 at 11:04
  • Actually, I remembered Why don't sensors have a wider aspect ratio?, which argues for even-more-extreme 16:9 over 3:2 rather than 3:2 over 4:3 — but I think covers the topic pretty well. – mattdm Dec 22 '16 at 12:28
  • Circular sensor would've remove all these doubts. – kmonsoor Dec 22 '16 at 20:03
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    Why mark this thread as duplicated when I have, in the question even mentioned the thread photo.stackexchange.com/questions/15298/… and what differences this one has from that? Clearly this thread contains very good answers and would be a good read for future fellas, looking for answers. – Tindra Dec 23 '16 at 7:15
up vote 19 down vote accepted

4:3 (1.33) is a very good ratio. It's aesthetic and easy to get a nice composition in both horizontal and vertical orientation. It's also closer to square, which makes best use of optics (larger aperture, less vignetting, etc). All photography ratios that were actually designed are pretty close to 4:3 (1.33) : 4x5" (1.25), 5x7" (1.4), 8x10"(1.25) large formats, and 6x6cm (1.00), 6x4.5cm (1.33) medium formats.

3:2 (1.5) is not a "real" ratio. It comes from a desperate attempt to stitch two existing but tiny 4:3 cinema frames together to get better picture quality required for still. The biggest reasons it's still around is compatibility with legacy equipment and people being taught to treat 3:2 as "professional". Which is nothing but an acquired taste, as 35mm 3:2 was introduced as amateur format back when 4x5" was professional.

The 16:9 ratio of your laptop is also not an artist's choice. It was chosen as a compromise between TV ratio of 4:3 and highly panoramic (up to 2.35:1) ratios of cinemas. It was chosen to semi-acceptably display both types of content without pan&scan process that's expensive due to human labor. One of the major reasons of inventing a new ratio was to create immediately recognizable brand for HDTV, like first digital watches had numeric faces just to make them instantly recognizable. And it that regard it was very successful. Displaying still photography was probably not even considered, computer screens were almost exclusively 4:3 at the time.

The square works best for photography, not only because of artistic reasons (which are subjective) but also because cost of optics depends on diagonal. So square makes biggest bang for the buck. On the other hand, the cost of screen depends on area. That means that the longer the better, because you get less area for a given diagonal. 16:9 21" screen has about 20% less area than 4:3 21" screen. So you can market wide panel at same price bracket, but with 20% larger profit margin, that's every sales department wet dream. Sensors being silicon go same way as screens, cost-wise, but price of optics still dominates the cost of modern cameras.

Now, the bottom line is that none of those matter today. You can easily turn on crop on an expensive DSLR (eg Nikon D3, D4, D810 to 5:4 or Canon 5DS to 4:3) or a cheap point-and-shoot to 16:9. You have access to free editing programs to crop, you can even do cropping on your smartphone. In photography cropping is cheap and easy, and with digital it's taken for granted.

So why do we keep using 16:9, 3:2 and 4:3? Because those ratios became recognizable brands of HDTV, DSLR and pocket cameras, respectively. Except from consumer awareness there is actually no reason to stick to any of those. From purely technical point of view, our screens would be best at something like 2.35:1 and our cameras at 1:1.

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    +1, although square isn't necessarily the optimal shape; a square gets more overall area, but a rectangle gets more usable width (or height). If your image circle is, say, 43.3mm in diagonal, you could have a square sensor of 30.6×30.6mm. But if you're making a composition at 2:1, the ideal sensor in the same image circle could be 38.7×19.3mm. That's only 80% of the area, but 26% wider! Since many people want to compose in rectangles, square isn't optimal after all, and 4:3 makes a decent compromise. – mattdm Dec 22 '16 at 16:12
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    @mattdm I meant that square is optimal from the technical point of view (maximizing area). Composing on square is another thing completely, only thing that's easier on square is getting rid of the "portrait or landscape" dilemma. – Agent_L Dec 22 '16 at 17:15
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    +1, but in my view (and this is not related to photographic uses) computer screens were better at 4:3 if you actually need to read from or work on them. Try buying anything squarer than 16:9 these days.... very frustrating. – Chris Peacock Dec 22 '16 at 17:32
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    Pan & scan isn't expensive--look at all the insane labor that goes into every other aspect of production. Studios simply wanted a chance to sell the same movie twice in widescreen and 4:3. – chrylis Dec 22 '16 at 21:22
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    Just because studios do other expensive things too doesn't mean pan & scan isn't expensive. – Lightness Races in Orbit Dec 22 '16 at 22:10

A 3:2 sensor ratio would be using a smaller share of the circular picture produced by the lens optics.
That means - compared to 4:3 - either you get less pixels/quality, need a smaller sensor (with the same pixel count), or need to modify the lenses to allow the sensor to be the same size. Neither of the three is desirable, and all three would affect the potential sales price of the compact camera.

If they could, the would make square pictures or even better circular pictures, to claim a much larger # of pixels at the same quality of resolution, without significant technical changes (only the sensor needs to be physically larger). Both are not convincing sales arguments, so 4:3 is it.

  • Wow! All bad logic, all very incorrect facts. 3:2 does NOT get less pixels/quality, need smaller sensor, nor need to modify the lens. That's blatantly wrong. Any lens COULD easily do square sensors, with same area. The sensor diagonal does need to be covered, but for any one given diagonal (the lens coverage diameter), a sensor fitting that lens diameter can give same megapixels for any aspect ratio. Same megapixels is Same Area. See scantips.com/mpixels.html – WayneF Dec 22 '16 at 16:17
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    @WayneF , what you are missing is that the density of pixels changes with the form factor, if you want to keep the same number of pixels overall. Pixel density however is the major technical issue, you can't just put them tighter for free. – Aganju Dec 22 '16 at 16:40
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    @WayneF you're assuming the pixel pitch can be changed to suit the aspect ratio, but that's usually fixed for a given process. Let's take as an example the Canon SX720, which is one of Amazon's best selling cameras at the moment. Image size is 5184 x 3888 for 20.2MP in the 4:3 ratio. Keeping the same diagonal and pixel pitch but changing to square (1:1) would be 4582 x 4582, or 21.0MP; a 3:2 ratio would result in 5392 x 3594 or 19.4MP. – Mark Ransom Dec 22 '16 at 17:25
  • No, of course I am NOT changing pixel size. Pixel size can be thought of as sensor width / pixel count across width (at least that is a maximum). The significance of aspect ratio is that height changes proportionately with the width change, one gets larger and one gets smaller, but still same product, same area, and the same diagonal (which remains the same in the circle of lens coverage). And sensor area is width x height, be it units of pixels or mm. Same megapixel count, same pixel size, same area. Just an aspect ratio change. – WayneF Dec 22 '16 at 18:14
  • You still don't understand the point: if you have 1000 pixel on 26 mm, you cannot just squeeze them onto 25 mm. Only 960 pixel will fit. The number of pixels that fits in a given distance is technologically limited. – Aganju Dec 22 '16 at 18:16

I think it's useful to look at a few questions like

... because overall, I think the more common desire is for sensors to be more square. Sure, laptop screens are wide, but filling a laptop screen isn't the only use for a photograph — or an optimal one. This fascinating mathematical article on the aspect ratios of classical paintings shows preference for 5:4 and 4:3. Wider formats like 3:2 (including, by the way, the "golden ratio" — don't get me started!) are way down the distribution curve. Of course, photographs aren't paintings, but the fundamental rules (well, guidelines) of composition are the same.

I think the real question is "Why is 35mm film 3:2, and why do digital SLRs follow that?". The first question I linked above, on 4:5 aspect-ratio DSLRs, provides several good answers to that, which are primarily:

  • Wider aspect ratios make mirror travel distance correspondingly less, allowing more compact and faster SLR designs, and
  • Eh, people are used to it.

If we invert this for compact and mirrorless cameras:

  • There's no mirror to worry about, so it's easier to go for a more-square design,
  • ...and "most people are used to it" now cuts the other way, more or less.

While others have given good answers, there might be an other reason. Mind you, I have no great sources to back the following up.

First is that film formats like this are old. Probably older then you and me. And in the beginning camera's were expensive toys. Go check with your family, ever newer generation has more pictures of them. Camera's and all that goes with it are getting cheaper with time. And they are a lot easier to use as well.

Second thing you might realise, 3:4 is used mostly by amateurs and 2:3 by professionals. An other difference between the users is the amount of money they are willing to spend to get pictures. Professionals will go to great lengths to get a "perfect" picture and equipment. Amateurs not so much. The last are perfectly willing to use APS-C and things like the original Olympus Pen.

Why are those great options for amateurs? Way more bang for buck! With an Olympus Pen original you get 2x more photo's with the same film! Now, the images are a bit more grainy. But film ain't cheap you know!

Now lets dig into some numbers.

Length film roll Kodak (and Ilford) 36 exposure film = 64 1/2 inch = about 150cm of usable film

2:3 = 24 x 36mm

  • 41.6 images = 150 / 3.6

3:4 = 24 x 32mm

  • 46.8 images = 150 / 3.2

2:3 Half-frame = 18 × 24mm

  • 83.3 images = 150 / 1.8

Or know as, we have done it this way for years, so this works and is good, so why change? & I should open links before diving into rabbit holes...

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    I dispute your categorization of "professionals" and "amateurs". Professionals have to make money. There are maybe a handful who make high-end art photography and have corresponding sky-high budget. Most professionals need to make every dollar count; they need reliable, durable gear which will get acceptable results without needing to nitpick about theoretical perfection. It's usually hobbyists using what's basically their play money, who have the luxury of chasing "perfect gear". – mattdm Dec 23 '16 at 15:03

When I had early digital cameras I missed the SLR aspect ratio. Most things I shot are either wide or tall, and when cropping the uninteresting part then I lost a significant part of the miserly pixel count. A 2 megapixel camera becomes more like 1.5 because I crop off the excess height. So I thought that the 4:3 sensor was wasteful, allocating pixels to regions that would be thrown away.

So I suppose film users had the same feeling back in the 60’s. Why spend money on film (and processing) when I would crop off a significant part of it? A wide (or tall, depending on how you hold it) frame used less film area for the desired image.

So how wide? I recall that in movies Todd-AO was quite an innovation to get 2.2:1 with one lens, and it’s expensive. Presumably making even bigger lenses and not using the top and bottom would be more expensive yet.

So, the picture is naturally a circle and you “waste” lens size by cropping off part of it. We don’t want our affordable 35mm hobby system to be as large and expensive as the medium format camera, and basing it on 35mm film stock with sprocket holes so the image is 24mm tall, 36mm wide (43mm diagonal) was a good compromise that didn’t make the lenses too big.

So why does the compact camera use 3:4? I wonder if it’s to inflate the megapixel value. For the same (small) lens diameter chosen, you can fill in more of the optical image with sensor material, and get more megapixels for the same pixel size.

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