Why are standard photo print sizes different proportions?

[CookingWithGas]

I am uploading files to Snapfish to be printed and am once again dealing with the fact that my digital images are 2336 x 3504 pixels, which match the proportions of a 4" x 6" print, but are different than 8 x 10, which are different still from 11 x 14. If I don’t want to let Snapfish make a mindless crop to fit, I have to resize each of my photos for the enlargement size I want.

If I decide to print something different than any of those sizes I need a custom mat.

How did we get here? Is there any rational reason for it or is it another one of those convoluted histories?

[Earl_Snake-Hips_Tucker]

I think we inherited those sizes from the old timey days because that was the size of the negatives.

[CookingWithGas]

@Earl_Snake-Hips_Tucker

I think we inherited those sizes from the old timey days because that was the size of the negatives.

They had 8x10 and 11x14 plates?

[GaryM]

I know they had 8x10 sheet film because I’ve used it. And cutting 8x10 print paper yields 4 4x5. But neither is the aspect ratio of 35mm film.

[Harmonious_Discord]

@CookingWithGas

They had 8x10 and 11x14 plates?

Going back to plates yes, and larger.

I think people should look at the camera film sizes for why photos are the sizes they are. There were a lot of film sizes besides 35mm. It also has to have been influenced by the size of the photo paper stock.

[Colophon]

I’ve often wondered this too. “35mm” film as used in still cameras has a standard frame size of 36 x 24mm, i.e. 3:2 so will fit a 6 x 4 photo perfectly. A lot of digital cameras, though, have a 4:3 aspect ratio, so some printers give an option of 6 x 4.5 in prints.

[Stan_Shmenge]

@GaryM

I know they had 8x10 sheet film because I’ve used it. And cutting 8x10 print paper yields 4 4x5. But neither is the aspect ratio of 35mm film.

And I think you have found the crux of the matter. The photographic plates were established before the Edison ratio, 4x3, it may be, although I don’t know, that the other ratios we see preceded the 4x3, which was originally used for movies. Because of the sheer volume of film consumed by the movie industry, it didn’t take long before 90+ % of the film being made and processed was for the movie biz, so economies of scale took over. It was a natural step to adapt compact film cameras to this format.

Anyway, that is my guess. In photography class, (years ago) we were always taught to think of the final print, and leave some margin on each side. Now that we have huge megapixels, and Photoshop, we can crop and choose all we want.

[Stan_Shmenge]

@Colophon

I’ve often wondered this too. “35mm” film as used in still cameras has a standard frame size of 36 x 24mm, i.e. 3:2 so will fit a 6 x 4 photo perfectly. A lot of digital cameras, though, have a 4:3 aspect ratio, so some printers give an option of 6 x 4.5 in prints.

And so they were using Edison ration film, but had to adapt to, what 6 perf? I think the answer is somewhere there.

[Stan_Shmenge]

Looking at a 35mm negative, it is 8 perf. So it is a matter of a mixture of formats, and of course you can’t get things exact. If you really want to get freaked out, check out all the formats they use for shooting movies. I work in that biz, and it is a freaking nightmare:

Previous and presently used aspect ratios

See List of common resolutions for a listing of computer resolutions and aspect ratios.
See List of film formats for a full listing of film formats, including their aspect ratios.

Comparison between several film aspect ratios.
Aspect ratio Description
1.33:1 35 mm original silent film ratio, commonly known in TV and video as 4:3. Also standard ratio for MPEG-2 video compression. This format is still used in most personal video cameras today. It is the standard 16 mm and Super 35mm ratio.
1.37:1 35 mm full-screen sound film image, nearly universal in movies between 1932 and 1953. Officially adopted as the Academy ratio in 1932 by AMPAS. Rarely used in theatrical context nowadays, but occasionally used for other context.
1.43:1 IMAX format. Imax productions use 70 mm wide film (the same as used for 70 mm feature films), but the film runs through the camera and projector sideways. This allows for a physically larger area for each image.
1.50:1 The aspect ratio of 35 mm film used for still photography. Usually called 3:2. Also the native aspect ratio of VistaVision.
1.56:1 Widescreen aspect ratio 14:9. Often used in shooting commercials etc. as a compromise format between 4:3 (12:9) and 16:9, especially when the output will be used in both standard TV and widescreen. When converted to a 16:9 frame, there is slight pillarboxing, while conversion to 4:3 creates slight letterboxing.
1.66:1 35 mm Originally a flat ratio invented by Paramount Pictures, now a standard among several European countries; native Super 16 mm frame ratio. (5:3, sometimes expressed more accurately as “1.67”.)
1.75:1 Early 35 mm widescreen ratio, primarily used by MGM and Warner Bros. between 1953 and 1955, and since abandoned.
1.78:1 Video widescreen standard (16:9), used in high-definition television, one of three ratios specified for MPEG-2 video compression. Also used in some personal video cameras.
1.85:1 35 mm US and UK widescreen standard for theatrical film. Uses approximately 3 perforations (“perfs”) of image space per 4 perf frame; films can be shot in 3-perf to save cost of film stock.
2.00:1 Original SuperScope ratio, also used in Univisium. Used as a flat ratio for some American studios in the 1950s, abandoned in the 1960s, but recently popularized by the Red One camera system.
2.20:1 70 mm standard. Originally developed for Todd-AO in the 1950s. 2.21:1 is specified for MPEG-2 but not used.
2.35:1 35 mm anamorphic prior to 1970, used by CinemaScope (“'Scope”) and early Panavision. The anamorphic standard has subtly changed so that modern anamorphic productions are actually 2.39,[1] but often referred to as 2.35 anyway, due to old convention. (Note that anamorphic refers to the compression of the image on film to maximize an area slightly taller than standard 4-perf Academy aperture, but presents the widest of aspect ratios.)
2.39:1 35 mm anamorphic from 1970 onwards. Sometimes rounded up to 2.40:1[1] Often commercially branded as Panavision format or 'Scope.
2.55:1 Original aspect ratio of CinemaScope before optical sound was added to the film in 1954. This was also the aspect ratio of CinemaScope 55.
2.59:1 Cinerama at full height (three specially captured 35 mm images projected side-by-side into one composite widescreen image).
2.66:1 Full frame output from Super 16 mm negative when an anamorphic lens system has been used. Effectively, an image that is of the ratio 2.66:1 is squashed onto the native 15:9 aspect ratio of a Super 16 mm negative.
2.76:1 MGM Camera 65 (65 mm with 1.25x anamorphic squeeze). Used only on a handful of films between 1956 and 1964, such as Ben-Hur (1959).
4.00:1 Polyvision, three 35 mm 1.33 images projected side by side. Used only on Abel Gance’s Napoléon (1927).

All this crap is up to the Director of Photograpy and the Director, etc.

No wonder your DVD’s need black bars, etc.

From Here.

[Napier]

I think photo paper and regular paper both exhibit a close-to-sqrt(2) aspect for the same reason. Each size can be cut in half to make the next size down.

So, half an 11x17 sheet gives 8.5x11, for regular paper. Similarly, cutting a 16x20 photo paper in half gives 10x16, and half that is 8x10, and half that is 5x8, and half that is 4x5.

Such a scheme can’t produce successive sizes of the same aspect unless the sizes are stepped by the square root of two, and the aspect is also the square root of two. For some reason, the idea of having an irrational number for a dimension seems to have scared them all off (even though the size only has a few meaningful digits anyway).

[friedo]

@Napier

Such a scheme can’t produce successive sizes of the same aspect unless the sizes are stepped by the square root of two, and the aspect is also the square root of two. For some reason, the idea of having an irrational number for a dimension seems to have scared them all off (even though the size only has a few meaningful digits anyway).

All metric paper sizes use this system, so pieces can be cut to obtain smaller standard sizes while retaining the same ratio. The system is based on size A0 which is exactly one square meter. Cut it in half four times and you get A4, which is close to the North American standard letter size (8.5x11 inches).

[Napier]

@friedo

All metric paper sizes use this system, so pieces can be cut to obtain smaller standard sizes while retaining the same ratio. The system is based on size A0 which is exactly one square meter. Cut it in half four times and you get A4, which is close to the North American standard letter size (8.5x11 inches).

But they still don’t retain the same exact ratio, they round it off:

"Paper in the A series format has a 1:sqrt(2) ~ 0.707 aspect ratio, although this is rounded to the nearest millimetre. "

ISO 216

Now, if you halve things an even number of times, you do retain the same ratio; it’s just that rounded ratios near the square root of two have to alternate above and below the exact value.