Who Decided 35mm Film Comes in 24 or 36 Exposures?

[peterc]

and for a while Ilford sold their HP5 in 72 exposure, on a special thin film base.

HP5 Autowinder. I have the special developing reel someplace.

 

[Chris101]

36 exposures:

 

[nikon_sam]

Wrong, wrong and again wrong...all of you missed the obvious...take a quick look at your camera's counter and you should notice that some of those numbers are red...And that's how they came up with 24 & 36...although my F2 was made incorrectly by having a red 20 and not 24...I believe this makes my F2 a rare collector's camera...

 

[DougFord]

The person who decided that film would come in 24 and 36 exposure loads was a guy named Eddy.

[FONT=&quot]Makes sense. This was Eddy’s bailiwick, after all.
He was a natural for figuring out how many things should fit into other things.[/FONT]

 

[David Hughes]

It took a while to find this; long, long ago bulk film came in tins of 50ft. So that's 10x 5ft lengths, which is 36 exposures...

Regards, David

 

[Roger Hicks]

It took a while to find this; long, long ago bulk film came in tins of 50ft. So that's 10x 5ft lengths, which is 36 exposures...

Regards, David

Dear David,

Except that no, it is't. A standard load was 63 inches, 1.6 metres. And besides, 50 feet is an imperial measure. Germany used the metric system by the time that the Leica came out, despite the fact that the mount is 39mm x 26 tpi (they were a microscope manufacurer, remember, and Royal Microscopical Society threads were the first in the world to be standardized).

Of all the explanations I've seen here so far, I have seen none more convincing than the one I put forward earlier: that 36 exposures, with one or two over if you were lucky, was the longest you could reliably stuff into a Leica cassette, the dimensions of which in turn were dictated by the size of the Ur-Leica which took 50 darkroom-loaded exposures (no cassette).

Had there been an internet at the time, no doubt it would have been full of people snivelling that Leica had screwed up and failed to fit 40 or 50 or some other round number of exposures in.

In those days, developed films were commonly stored in the full roll, but as soon as they began to be cut and stored in sleeves, 36 was an obvious number as you can cut 9x4 or 6x6; the only other obvious candidate is 35, cut to 5x7 or 7x5. You can't get 40 or even 39 in; 38 is 2x19; 37 is a prime number; 34 is 2x17; 33 is 3x11; 32 is 8x4 or 4x8, but why not have the extra 4 frames?

One frame-plus-rebate, measured from my MP, is 39.5mm, which x36 is 1.422 m. Add two frames on the spool end (the spool on a Leica cassette is slotted and takes the film trimmed to a blunt point) and you're up to 1.50mm, then a 10cm tongue and a couple of blank frames in case of fogging at the beginning and -- surprise! -- you're at 1.58 metres or 62.2 inches. At this point, 1.6 metres/63 inches is unanswerable.

Now: it's 1933 or so, and Perutz, Kodak and others want to sell their film for Leicas and Contaxes; 36 exposures (or 37 if you're lucky) is already established; what are they going to go for?

All this stuff about Barnack's arms and so forth is not really supportable, given that the Ur-Leica used a longer loading; Kodak's deciding on 36 exposures is clearly not the case, given that this loading was already well established and that the two most popular 24x36 cameras counted only up to 40 anyway; how much more explanation is really needed?

Cheers,

Roger

 

[Dave Wilkinson]

All this stuff about Barnack's arms and so forth is not really supportable, given that the Ur-Leica used a longer loading;

Cheers,

Roger

Barnack actually had very long arms, and was also responsible for the term 'chimping'!
Dave.

 

[varjag]

Roger,

In darkroom, my hands stretched measure out 36 exposure roll, give or take one frame. So I'm sticking to the Barnack story, for vanity from perceived anthropometric likehood to him 🙂

 

[sepiareverb]

...All this stuff about Barnack's arms and so forth is not really supportable, given that the Ur-Leica used a longer loading...

Not surprised that was a legend.

 

[KenR]

The shift from 20 exposures to 24 exposures ocurred in the late 70's, so most cameras made before then have the 20 and 36 counters in red. Sorry, not a collectors item.

 

[JohnTF]

In the dark recess of my memory I find this bit of trivia; a cubit is about 5’6” the height of a man, but don’t quote me or complain if you can’t get two of everything on

Used to teach this stuff, human derived units were, digit, palm, cubit, foot, fathom, yard. An inch was three barley corns. 5'6" would be closest to a fathom.

A Cubit was the distance from the end of your middle finger to your elbow.

I seem to recall the standard foot in question was Charlemagne's, and the yard was an English Kings' nose to outstretched finger, but it was not common to have different units with the same names, and we want politics to be logical in a country that still cannot deal with the metric system (SI).

Truth be told now, our young people do not know either system, and will never properly use Avoirdupois, the French name for the English system only used in America, because they generally cannot deal with fractions.

We made cubit sticks, measured the room in cubits, palms and digits, and then when I asked for the area, they were happy to give the Metric system a go.

As I recall, Roger wrote an interesting article extolling the virtues of 5x7 cameras, as they could, by merely swapping holders, take a plate size, Avoirdupois size, and metric size, plus the size of a contact print was pleasing.


Regards, John

 

[sepiareverb]

Used to teach this stuff...

And 36 exposures wasn't part of the syllabus? 😀

 

[JohnTF]

And 36 exposures wasn't part of the syllabus? 😀

Had I seen Tom A's You Tube cartridge loading video, I would certainly have included it. ;-)

After loading my first 100' of free expired Tri X entirely by hand in used Kodak cartridges, I managed to find the $5 to buy a bulk loader, then the counting thing began.

John

 

[ZorkiKat]

In those days, developed films were commonly stored in the full roll, but as soon as they began to be cut and stored in sleeves, 36 was an obvious number as you can cut 9x4 or 6x6; the only other obvious candidate is 35, cut to 5x7 or 7x5. You can't get 40 or even 39 in; 38 is 2x19; 37 is a prime number; 34 is 2x17; 33 is 3x11; 32 is 8x4 or 4x8, but why not have the extra 4 frames?

The 6 frames/ 6 strips arrangement also fits on an 8X10 sheet nicely to proof the entire roll. 5 F(rame)/ 7S(trips) also fit, but with one frame less...

The same could be said of the 120/220 roll films- 6F/6S or 4F/3S for 12 exposures, or 2F/4S for 6X9, or 4F/4S for 6X4.5 also fit this paper format well. So were these considerations too?

Makes sense. This was Eddy’s bailiwick, after all.
He was a natural for figuring out how many things should fit into other things

So was Eddy responsible too for setting 78 rpm as the speed for phonograph records? Did RCA consult him to figure 45rpm and Columbia for 33.333 LPs? 😀

 

[Seele]

While Kodak made what we call the 135 film, as in a length of 35mm perforated film in an ostensibly disposable light-tight cassette designed to be compatible with both Contax and Leica, and made the Retina series to take them as a mean to popularise it, the same form factor of film packaging was first made by Agfa about a year before.

 

[rbsinto]

So was Eddy responsible too for setting 78 rpm as the speed for phonograph records? Did RCA consult him to figure 45rpm and Columbia for 33.333 LPs? 😀

You're just being silly now.
The record guy was Eddy's Brother-in-Law, Phil.

 

[David Hughes]

Dear David,

Except that no, it is't. A standard load was 63 inches, 1.6 metres. And besides, 50 feet is an imperial measure. Germany used the metric system by the time that the Leica came out, despite the fact that the mount is 39mm x 26 tpi (they were a microscope manufacurer, remember, and Royal Microscopical Society threads were the first in the world to be standardized).

- - - Snip! Snip! - - -

Cheers,

Roger

Hi,

Well yes would be my short answer but I looked into all my old books from those days and they say 5 feet, which is weird, but as none are English I wondered.

Also, my experience of these things is that minor details like this are not designed for anything but ease. So 1 or 1½ metres fits the bill. Then I imagine - once the great stupid public - got their hands on the cameras & cassettes and were less careful with them; the commercial version settled on 63" to give a margin of safety. The alternative explanation is that 160 cm is exactly 63" and therefore a common measure in both systems: which backs the "commercial" argument.

As for the microscopes, I've often wondered how many pieces were off the shelf. I'd love to get my hands on the entire range as sold/made in (say) 1912 to find out. Of course, off the shelf could mean finished parts or else the raw materials. Why make the cassette an inch in diameter for example? Would Barnack have designed a lens specifically or was he after a small camera and picked something suitable to go in front of it? Again using stock parts, perhaps?

I doubt if we'll ever know. Even people who worked with Barnack offer differing stories and dates for things happening. I just wish I had the time to look into it all but (again) previous experience says I need to be 20 years younger, rich and speak German.

Regards, David

 

[nikon_sam]

So then, Phil came up with the plastic thingy you had to put in the 45's to get them to play on the stereo...you're telling me Phil came up with those too...???

 

[Roger Hicks]

Dear David,

I've never measured the cassette and didn't know it was an inch, which is, as you say, an interesting fact.

Here's a suggestion, though. With most lathes of that era, there were separate gear sets for metric and imperial. As a microscope manufacturer, Leitz would have had most of their machine tools set up for imperial, because that was the standard -- just as we use 1-3/8 inch film (half of 2-3/4 inch Kodak film, slit and perforated) and cut-film registration is standardized in inches. For that matter, the standard tripod socket threads are 1/4 inch and 3/8 inch.

If you load 5 feet dead, you're in effect knocking off two of the blank exposures at the beginning of the film, so the 'carelessness' theory has something to recommend it. On the other hand, so does sloppy translation: the original Focal Encyclopedia (1956) gives 'about 65 ins or 1.6 metres'; they also refer to 'unspooled bulk lengths of 25, 50 or 100 feet, or of 5, 10, 25 or 30 metres' (page 1070) and we may fairly assume that metric bulk loads were more normal on the continent. Somewhere I have a sealed, German-market 1936 tin of Agfa 35mm film and when I find it again I'll check the nominal length.

Cheers,

R.

 

[Seele]

I think a proper length for 36 exposures, with Leica-type full leader trim, should be 1.64m.