Why do they call it 135?

[EASmithV]

I've never quite understood where the 1 in 135 came from. Can someone clarify? It's always bugged me.

[sandermarijn]

One of those questions I've already been afraid to ask. Thanks for sticking your neck out for all of us in the same position.

My guess is that there is nothing to it, that it's just a convention. Of course it would be more satisfying if there were some technical explanation.

[MattKing]

It was just the number assigned to the film format by Kodak when they first designated that format by number.

Some of those film format numbers have a slight connection with the size, while others don't (e.g. 120 and 620 - same film, different spool).

Some of those film format numbers were assigned consecutively, while others aren't.

Some film format numbers were used, then went out of production, and then the number was re-used for another format later.

Here is a Wikipedia article: http://en.wikipedia.org/wiki/Film_format

[Peter de Groot]

It is the name Kodak invented for it:

http://en.wikipedia.org/wiki/135_film

Google is your best friend in this case :-)

[jorj]

My understanding is that it's somewhat arbitrary. In the early 1900s, someone (or someones) decided to standardize the naming of film, and started naming the types of film at 100 (or, perhaps, 101). Since all of the designations started with a "1", the name "135" was born.

Now, that doesn't explain names like "220", which one could readily assume is just "120 is one roll; 220 is two" - or 645, which is 6 x 4.5. Aah, standards; good thing we have a million of 'em.

[sandermarijn]

Is there any logic behind this? 135 is a 1 in front of the film's width. 120 is a 1 in front of (?). Hm, probably no logic at all.

[MattKing]

Is there any logic behind this? 135 is a 1 in front of the film's width. 120 is a 1 in front of (?). Hm, probably no logic at all.

No consistent logic. Some formats have some though (e.g. 126 is 26mm x 26mm).

[railwayman3]

Up to, maybe, the early 1960's there were 36 exp 35mm refills available (presumably mainly for the Leica and Contax reloadable cassettes), with the designations 635 and 935.
Not sure which-was-which without checking, but one was for daylight reloading (with a paper leader) and one for darkroom.

[Pumalite]

Maybe is a meter of film with 36 frames in it

[benjiboy]

My understanding is that it's somewhat arbitrary. In the early 1900s, someone (or someones) decided to standardize the naming of film, and started naming the types of film at 100 (or, perhaps, 101). Since all of the designations started with a "1", the name "135" was born.

Now, that doesn't explain names like "220", which one could readily assume is just "120 is one roll; 220 is two" - or 645, which is 6 x 4.5. Aah, standards; good thing we have a million of 'em.

My understanding agrees with yours that they started numbering film types with 100, however 645 is 16 on 120 film not a film designation the image size is 6X4.5 centimetres, and 220 is twice 120, or 24 on 120.