35mm film: aspect ratio of negatives, prints, and enlargements

Factual Questions
1

I recently went to the photo shop to get a 35mm picture enlarged for a friend who wanted to buy it; he already had an 8x10 inch frame handy, so that’s the enlargement size I requested. I knew the picture I was blowing up filled the frame and when I got the enlarged shot back, I saw it was obviously missing a significant portion of the picture.

“What’s this?” I ask. “You chopped off part of the picture.” The girl behind the counter looked at my blankly. “Try again and please do it right - you know, I wanted the entire picture enlarged!” So I give it back to them for another try. The next time I get the enlargement, the whole picture is there all right, but it’s an 8x12 inch picture!

At a loss to explain this, the clueless counter jockey brings in her manager who clarifies why everything was screwy. I checked his figures when I got home, and sure enough, he’s right: It’s impossible to get an 8x10 inch blowup that matches the negative I gave them.

A 35mm film negative measures 2.4x3.6 cm, giving it a 2x3 aspect ratio. Standard size prints of 4x6 inches conform to this 2x3 ratio, so the prints you get match the negatives you see in the sleeves. So far, so good.

But no standard enlargements can match the negative. The ‘normal’ sizes of 4x5 in, 8x10 in, and 16x20 inch enlargements all have a 4x5 aspect ratio, effectively lopping off a 1/6 of your picture. So the first enlargement I got was blown up to an 8x12 and then cropped down to an 8x10. If I want the entire subject in the picture with nothing cropped (which I do), I’m going to have to buy a custom sized frame to fit my 8x12 inch photo. Arrrgggh!

So - and here’s the question - why??? Why do standard size enlargements not preserve the 2x3 ratio of the original film?

And finally, on related note, what the heck does 35mm denote? I always understood it to be the diagonal measurement of the film. However, in my quest to grok film sizes and aspect ratios, I found that’s not the case - not by a long shot. Apply a little Pythagorian magic to the 2.4x3.6 cm measurement of the film and you find that the diagonal should be 4.326661530557 cm across, which I also corroborated with my ruler (at least to the 4.3 part). That’s 43mm film, not 35!

So what is 35mm measuring?

2

Skip the dead Greek guy–this ain’t a TV. 35mm=3.5cm=width of the film, which for some reason you have as 3.6–perhaps a faulty rounding-off somewhere.

3

I considered that too and measured twice just to make sure. The film definitely measures 3.6 cm in width. It’s not just close – it’s exact. Measure some yourself if you’d like.

4

STARK was measuring the image size. The 35 mm refers to the width of the entire film, including the perforations. Originally, 35 mm still cameras were made to use already existing 35 mm movie film.

Standard print sizes were probably established when a lot of competing camera formats were still in popular use, producing negatives in a variety of aspect ratios. They probably stay that size because that’s the size picture frames are manufactured in.

5

The width of the film is 35mm. The size of the image 24 x 36 mm so the ratio is 1:1.5

To conserve the entire picture you need to conserve that ratio

6

The entire width of the film is 3.6cm with .05 overlap for film guides, on the edge. The image is 3.5cm.

Folks with their own dark room equipment will do custom enlargements for you where you can actually talk with the person who is going to make the print. They can plan a good crop position to get you what you need. Most pictures need cropping anyway, and good photo houses will let you select from sample positioning templates for the best cropping fit.

Standard frame sizes are relics of pre-photographic times, as are standard matting materials. Canvas is available on stretched frames of those sizes, and the frames fit around those. Photography came at the framing industry late, and was easily able to conform after the fact of film size. Now days, computer printing is reaching the level of fidelity that makes framing more than just occasional. Turns out printed stuff is yet another non standard size, and you have to cut your own mats, or make your own frames, or both. Bummer.

Tris

7

The image is 36mm x 24mm, but the film (measured edge to edge) is very close to 35mm (a little over 5mm on each side of the 24mm wide image on each of the film for sprocket holes and fudge space).

Ugly

8

Film has historicaly come in all sorts of sizes. For most of photograpy’s history most film came in single sheets usually in 10x8" or more recently 5x4" which is still very much in use today for high quality commercial work. Traditional paper sizes were designed to work well with these formats.

9

I have a very good friend in the one-hour photo processing biz, so I have a litte exposure (get it?) to this subject. I can’t answer everything, but I can at least address some aspects of your Q’s.

Mini-lab photo processing machines (which is what all the non-custom places use) use print paper that comes on big rolls – like toilet paper. Naturally, the rolls come in various fixed widths (and, several hundred feet in length).

Now, say your drug store’s machine is set up to use 5" wide rolls of print paper. Well, that limits one of your dimensions right there. (That is, either the H or W must be 5".) Then, because they don’t want to offer oddball sized prints, they use a second dimension that fits the image to the next smallest 1/2 inch.

So, a machine that uses 5" wide rolls can make, say, (I’m making these dimensions up…) 5 x 7 prints, and 4 x 5 prints. Because the ratio is not identical, they’re bound to lose some of the image at the edges.

Stark, does this help answer why it was so hard to get a full image from your local processor? If not, I’ll ask my buddy for more insights.

10

>> The entire width of the film is 3.6cm with .05 overlap for film guides, on the edge. The image is 3.5cm.

WTF??!! Why do people make up stuff and post it here? Please measure a piece of 35 mm film. It is called 35 mm because it measures 35 mm. If you measure it and it comes to 36 mm your measuring device is off (what are you using?)

11

Maybe his film was made by the same people who used to make Benson & Hedges cigarettes.

12

Or maybe he is measuring with his dick and it waxes and wanes depending with what’s in the picture :slight_smile:

13

See film dimensions here

14

To that list, you can add the following formats which had significant popularity at one time:

35mm half frame - 18 x 24 mm image.
126 instamatic - square.
110 instamatic - 12 x 17
127 roll film - 4 cm wide roll film.

The instamatics were very popular snapshot cameras in their day, and a lot of prints were processed in those formats. The popular Kodak brownies which preceded the instamatics took square negatives on 127. Medium format also includes a 6x9 ratio, and there were several 16mm formats. For a while, Kodak also pushed the disk film camera, which IIRC, was a 4 x 5 aspect ratio.

If you dig up the history, when Kodak introduced roll film, they changed sizes and shapes of negatives with practically every model.

15

Because I was posting in my sleep?

The film is 35mm wide, the film guides take up a portion mostly along one side (about 9mm total), and the image is 36 cm long. The film is named for the width of the film, not the length of the image.

Really sorry, but believe it or not, at the time, I thought that was what my original post said!!

Duh.

Tris

16

Not on any of the film I have lying around (which is probably 300 to 400 rolls of 35mm film, both negs and chromes).

The image is centered on the film stock, with equal size areas down both sides (a little over 5mm each) for sprocket holes and a little fudge-factor space.

Perhaps this is true of 35mm movie film stock? I haven’t seen any in years and don’t recall, although my memory is that movie film stock is also physically symmetrical, but the image is offset to allow for the optical soundtrack. Although that memory goes back years, and I could be confusing 16mm with 35. Or I could just be up in the night.

Anyway, standard 35mm film for still cameras is symmetrical, and the image is centered between two sets of sprocket holes on every camera I’ve used. This includes a couple of dozen different pro/am 35mm SLRs, a few rangefinders, 4 or 5 point & shoots, and even a 35mm roll film back I’ve got for an old medium format 4x5 Speed Graphic.

Ugly

17

Triska, just you wait until I find that wet noodle :slight_smile:

18

As I said, 35mm still cameras were originally designed to use 35mm movie stock. But this was in the early 1920’s a few years before talkies came in. Whether modifications affecting sprocket placement happened in the last 8 decades, I don’t know.

19

First of all, when I said I measured the film to be 24x36 mm, I was not being entirely clear. I was, in fact, entirely wrong; I measured the image on the film at 24x36 mm. The width of the entire celluloid strip, from sprocketed edge to sprocketed edge is indeed 35 mm, as yabob, sailor, and RJKUgly all said and the site ticker linked to corroborates.

So I now know from whence the designation 35mm comes. It’s a measurement of the film’s physical width and has nothing whatsoever to do with the image size. Of course. Well, that was easy enough.

But what isn’t so easy is the answer to my question about standard enlargement sizes and standard frame sizes.

Enlargements first: Why does MotoPhoto list an 8x10 enlargement as a standard size increase? If they were catering to professionals who took large-format 4x5 pictures, it would make perfect sense. But I imagine MotoPhoto handles amateur photogs almost exclusively, and amateurs shoot almost exclusively in 35mm, a 2x3 format. Offering as standard an enlargement that alters the aspect ratio of the original picture makes no sense - unless of course they do so in order to create a finished picture that will fit in a standard sized frame. This, I imagine, is the case.

If true, the blame gets shifted to the frame makers: Why then are standard-sized mass-produced frames offered in a 4x5 format (like 8x10 and 16x20)? Again, if the frame manufacturers were catering to professionals, this would make sense, but again, I imagine most people who buy an off-the-shelf ready-made frame are decidedly not professionals.

I realize that not every frame made is destined to hold an enlarged 35mm photograph, so there’s no cause to make them all in a 2x3 format, but it seems reasonable to assume that those sold to cookie-cutter photo shops like MotoPhoto will. Why not manufacture such frames to conform to the aspect ratio of the pictures they will almost certainly hold?

Triskadecamus suggests that “standard frame sizes are relics of pre-photographic times,” but surely some frame maker has by now figured out that 35mm cameras are pretty popular. Why not make a frame that caters to that popularity?

20

Besides just plain old resistance to change, I can WAG a couple of reasons.

  1. The viewfinder in virtually all 35mm cameras show less of the scene than actually appears on the film.

Years ago, some SLR cameras had (or at least approached) a 100% view finder, but these days 90% is about it, and some cameras only get high 80s (I doing these percentages from memory, so I may off a bit, but not by more than a couple of percentage points, I think).

Non-SLRs (where you view the scene through a separate set of optics than the lens used to take the actual picture) are usually even worse. Since they can’t (by definition) show exactly what the film will “see”, they have to approximate. The camera manufacturers want to head off people complaining that they when they took that last picture of their now deceased father, Dad’s head was clearly in the viewfinder, but it’s cut off in the picture (although you can’t avoid this problem completely, especially when shooting very close to the subject. Parallax error inherent in separate off-axis shooting and viewing optics make sure of this). So they err on the side of safety and make the viewfinders (or the alignment marks in the viewfinder) show a little less than the best guess of what will actually hit the film.

What does this have to do with a standard enlargement sizes? Because of the inaccuracies in most viewfinders, printing a little less than what is on the film may actually get you a picture that is closer to what you saw in the viewfinder than printing a full frame. Not a great reason, but it may contribute to the thinking that there is little need to change the long-standardized sizes.

  1. Most amateur photographers drastically overshoot the scene (meaning that the main subject is a small bit in the center of the picture). The wide angle and short zooms on virtually all inexpensive camera are partly responsible for this.

But this is caused more by the fact that that very few people realize the difference between what they see and what the camera sees. The human brain does enormous “image processing” on the fly. Part of that processing is to ignore parts of a scene that aren’t interesting, and focus on those that are. So when they see Aunt Patty making those great tennis shots, they don’t understand why the pictures show a tiny little figure surrounded by the tennis court, the stands, the parking lot, 20 degrees of sky, and their own feet.

The slight extra enlargement and cropping of these pictures not only doesn’t hurt, but probably helps slightly.

Again, this isn’t a great reason, but (again) probably contributes to the “if it ain’t broke, don’t fix it” attitude.

When I shoot, I try to “overshoot” a little, knowing I can crop in the darkroom. This takes care of the problem most of the time. When framing tightly, I allow a little extra on the long axis, keeping that 1.5 to 1 ratio in mind. And where artistic considerations simply don’t allow for a standard aspect ratio, then you get a custom matte and/or frame. As a bonus, the custom sizes frequently make your shots stand out from the crowd anyway, so it’s not all bad.

Well, that turned into a much longer post than I thought, so I’ll bail now, while a couple of you may still be awake.

Ugly