Camerapedia
Advertisement

Inch sizes and centimetre sizes[]

We read:

It uses 120 film to make 6×9 cm negatives. Since it was made in Britain, 2 1/4 × 3 1/4 inch is probably a better way of describing the format.

This strikes me as bizarre.

The better way of describing the format is to start by paying attention (i) to its name at the time, (ii) to the facts, and (iii) to the readers' convenience. We'd hope that these three would lead to a single description; if, as is likely, they didn't, we'd reconsider.

(i) 2 1/4 × 3 1/4 inch (I think, though I haven't checked)

(ii) 2 1/4 × 3 1/4 inch (I think), and if so then about 5.7 × 8.25 cm.

(iii) I'd hope that we can now expect even the Americans to be familiar with the metric system. If so, and if (ii) is correct, then about 5.7 × 8.25 cm.

Calling "6×9" what's obviously far short of 6×9 seems odd to me, but it's an established convention, and moderately informed readers will know that it's a fiction. (Incidentally, this site should somewhere explain that it is a fiction.)

What does stick in my throat is the habit of Japanese (and other?) publications that are otherwise intelligently written to refer to the output of the Fujica G690 etc. as "60×90mm". Bogus precision or complete stupidity?

I remember that my father — a research chemist who had very little patience with "Imperial" measurements and suchlike mumbo-jumbo and indeed was a bit of an SI fanatic — would always refer to the output of his Microcord as "2 1/4 × 2 1/4". It's better to use obscure units accurately than to use even SI units inaccurately. -- Hoary 20:54, 17 June 2006 (EDT)

Here is some guess about the origin of this mess, all this needs research to be confirmed:
Originally the film plate cameras produced in continental Europe took plates whose size was measured in centimeters, and this was surely the true size, (I think this is the case of the 6.5×9cm and 9×12cm sheet film still sold today). The British cameras used other formats, some subdivision of the 'plate', that is originally the size of a plate of glass used to make windows or windowed doors, expressed in inches. The American used yet other formats, expressed in inches too, but unrelated to the 'plate', for example the 4×5in.
When Kodak introduced the rollfilm, it was surely expressed in inches too, for ex. 2 1/4 × 3 1/4 for the 120 film. That is very close to the 56×84mm dimensions used today, the difference being explained by the manufacturing tolerances of the time.
When the European makers began to introduce rollfilm cameras, it was out of question to advertise them with a size in inches (while today everybody gives the size of a computer screen in inches, sometimes the world is running backward..), so they invented false sizes in centimeters, rounding the size to the above centimeter (56mm -> 6cm, 84mm -> 9cm). They could have said 5.5×8.5cm, but they surely did this for commercial purpose. Another justification was that the pictures produced by these essentially amateur cameras (the first rollfilm ones) were often contact-printed only, at a time when enlarging was an expensive operation. On the border of all the contact prints that I have seen of this period, there is a white margin, and I guess that the papersize was indeed 6×9cm. So here we are, these cameras indeed took 6×9cm pictures, in the form of contact prints, white margin included.
Please consider this is only guesswork, not to be included verbatim in a page, but I really think this version to be quite close from the truth.
--Rebollo fr 05:02, 18 June 2006 (EDT)
Advertisement