35mm (sensors and film) and why

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I have been trying to find out why 35mm film (and presumably full-frame digital sensors) are actually not 35mm at all, but 24 x 36mm.

I am ready to be corrected but as far as I gather, original 35mm film stock was (is) 35mm from side to side in cine cameras (top to bottom in SLR's) but taking away the sprocket holes, the effective film width (height) is 24mm. Is it that the exposed bit is 35mm long with an extra bit to separate the frames making it 36mm?

Is this correct or am I talking b*****ks? I really should know, I've been using film since 1973.
 
Ever reliable wiki ( not like my school days) says the film top to bottom is 35mm https://en.wikipedia.org/wiki/135_film. Part of me thinks digital went to 35 due to locked in syndrome and everyone on the planet having 35mm lenses, they could have gone in many directions back when there were no smartphones
 
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You are right in all respects, 35mm film (or 135 format) is 35mm from side to side. It is all emulsion coated, but the rebates have edge markings and then there are sprocket holes. So the effective width is somewhat reduced. It would be hard (says the man who scans his own films) to make the exposed frame much bigger. There are some who have exposed the sprockety edges for artistic effect ( @Harlequin565 ). But for most purposes, that's your 24mm.

The other dimension is more free, but convention shoehorns us into 3:2.
 
I believe (though I might be a mile out) that it’s 35mm cine* film, the frame being 24 x 18 or something and the diagonal of that is 35mm?

*That’s the bit we miss, the film was designed to travel vertically
 
acrobatic_Citron said:
Ever reliable wiki ( not like my school days) says the film top to bottom is 35mm https://en.wikipedia.org/wiki/135_film. Part of me thinks digital went to 35 due to locked in syndrome and everyone on the planet having 35mm lenses, they could have gone in many directions back when there were no smartphones
Click to expand...

Boots said:
You are right in all respects, 35mm film (or 135 format) is 35mm from side to side. It is all emulsion coated, but the rebates have edge markings and then there are sprocket holes. So the effective width is somewhat reduced. It would be hard (says the man who scans his own films) to make the exposed frame much bigger. There are some who have exposed the sprockety edges for artistic effect ( @Harlequin565 ). But for most purposes, that's your 24mm.

The other dimension is more free, but convention shoehorns us into 3:2.
Click to expand...

Phil V said:
I believe (though I might be a mile out) that it’s 35mm cine* film, the frame being 24 x 18 or something and the diagonal of that is 35mm?

*That’s the bit we miss, the film was designed to travel vertically
Click to expand...



Phil, the diagonal would be 30mm with a frame 24 x 18, but I see your thinking, I thought it was that too at first, but 24 x 35 makes a diagonal of [about] 42, so that didn't work either.

The top two posts reference 135 film and if I'd looked at 135 instead of 35mm, all would have become clear; as is shown on this Wikipedia entry: 135 format
 
acrobatic_Citron said:
Ever reliable wiki ( not like my school days) says the film top to bottom is 35mm https://en.wikipedia.org/wiki/135_film. Part of me thinks digital went to 35 due to locked in syndrome and everyone on the planet having 35mm lenses, they could have gone in many directions back when there were no smartphones
Click to expand...

The APS system (remember that?) was one 'recent' attempt to decrease the size of the film, and to miniaturise the equipment but didn't catch on, especially when the technology on the films used to make the quality comparable with 35mm film was imported into the larger film products e.g. Fuji Astia. The only real legacy of APS was the APS-C format, but none of the APS camera/lenses are compatible with the later digitals...
 
Not quite the only legacy. As you say, "the film technology used to make the quality comparable with 35mm film was imported into the larger film products". The biggest bonus of APS was to the less technically minded (and less dextrous) - far easier to slip an APS cassette into the cameras than to load a 35mm film - even the MiL could manage it!
 
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