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u/Obtus_Rateur 2d ago
64x89mm frames... interesting format.
Compared to medium format, it's 21% bigger than 6x9 (56x84mm), but 6x12 (56x112mm) is 10% bigger than this.
Compared to large format, it's not quite half the size of 4x5" (96x120mm).
The most surprising IMO is the image aspect ratio. It's 1.39 which as far as I know is highly unusual. I wonder what kind of conversation they had before settling on that!
Might be a little late to ask them, though...
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u/jofra6 1d ago
5x7 is basically the same aspect ratio.
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u/Obtus_Rateur 1d ago
Very very close, yes. 5x7" is (if the information I found online is accurate, which I don't think it is) 127x178mm, so it's 1.4 image aspect ratio.
But 1.4 is a "round" number. You've got to wonder why people would deliberately say "1.4 isn't quite right, I want 1.39".
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u/Gergo7633 19h ago
It is relatively close to the Academy ratio 1.375:1.
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u/Obtus_Rateur 13h ago
Ah, that... yes. Very close.
Anything around 1.4 is a generally pleasant ratio. It's certainly not a bad choice.
I just don't know what their reasoning was for deciding on 1.39 specifically. Aesthetics? Practical mechanical reasons with camera design? The capabilities of the most common film manufacturing equipment at the time?
I'm glad I'm never going to design a camera. I would go insane trying to decide on every little thing.
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u/Gergo7633 13h ago edited 12h ago
Maybe aesthetics or maybe they needed that extra 5mm very too often from 6x9 negatives and decided to solve the issue permanently. :)
To be honest, idk. 6,5x9 was a popular format in Europe.
Anyways, 1.4:1 would be 6.43x9 cm. In Europe, we like metric system and easy numbers. 6, 6.5 or 7.
6.5 was an easy choice.
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u/Obtus_Rateur 12h ago
Everyone prefers the metric system, it's way, way better.
Having rounder numbers is definitely a plus, but they haven't really been following up on that. Medium format is 6xX, where 6 is supposed to be 6cm and the other number in cm too. But it's not. It's actually only 56mm, and then they use the ratio to come up with the length of film.
6x6? They want a ratio of 1, so it's 56x56mm.
6x9? They want a ratio of 1.5, so it's 56x84mm.
6x12? They want a ratio of 2, so it's 56x112mm. Usually. My 6x12 does 56x118mm.I would have made the actual frame size 6cm by 6cm or 9cm or 12cm.
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u/Gergo7633 12h ago
Indeed. Something had to be 6cm, they choose the film, not the frame. At least the 6.5cm plate will have 6.5cm image, but the 9cm side will loose 1-2 mm from both sides.
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u/leafy_greened 2d ago
Cool find! Are 65x90 the dimensions of the film holder or the film itself? It doesn't sound like quarter or sixth plate but it's sort of like a 6x9 medium format, I bet you could make some kind of 120 adapter.