120mm roll film widths and frames

Since 120mm roll film can be used for pictures of different widths,
depending on the camera, what width do the frame numbers on the back -
that appear in the little window in the camera back - refer to?

And if you're using a different width, how do you know when you've wound
on exactly one frame?

Daniele

 

On Wed, 22 Dec 2010 11:57:35 +0000

The backing paper has frame numbers for 4.5, 6 and 9 cm frames arranged
like so (view with fixed-width font):

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 2 3 4 5 6 7 8 9 10 11 12
1 2 3 4 5 6 7 8

and the window in the back lines up with the appropriate row. Cameras
that use other frame widths like 7 or 8 cm need mechanical counters or
a use system involving two or all three of the standard spacings with
windows at different offsets. Multi-format cameras e.g. those that can
shoot either 6x6 or 6x9 have multiple windows, which may be
automatically selected when the mask is changed. Some cameras have
different windows for pan and ortho film because the safelight filter
requirements are different (dark green and red respectively).

 

Sorry, but this is something that gets on my nerves - there is no such
thing as "120mm" film (except possibly for special purposes like aerial
survey). The is a Kodak standard film size "120", approximately 60mm
wide, the same width as 220 and 620. This is one of many Kodak film size
numbers, other common ones are 135 - 35mm wide movie film in cassettes,
126 - film cartridges for Instamatic format cameras and 127 - rollfilm
approx 40mm wide. Few, if any of these type numbers have any direct
relationship to the physical dimensions of the film - you might as well
say that the M1 motorway is one mile long!

120 film (first introduced at the beginning of the last century) has a
paper backing, with frame numbers for various common formats printed
across the width, such that a window in the camera back will align with
the appropriate numbers for the format in use. However,this technique
became obsolescent over 50 years ago, and most modern medium format
cameras have winding mechanisms which automatically advance the film
to the correct position.

Also, some cameras are built for formats (such as 6x7cm) which don't
correspond to the frame numbering printed on the backing paper, and 220
film allows twice as many frames as 120 by removing the backing paper,
apart from a header and trailer, thereby wasting less space on the spool.
However, as well as having nowhere to print frame numbers, 220 film would
immediately be fogged if you opened a window in the back.

For more info, see Wikipedia:
http://en.wikipedia.org/wiki/120_film

 

People will use imprecise terminology, but it's not that important - 120
rollfilm isn't going to get confused with something that doesn't exist,
is it?

 

If it's the worst thing that gets on your nerves, then you're living an
enviably easy life!

Daniele

 

If it's the worst thing that gets on your nerves, then you're living
an enviably easy life![/QUOTE]

Absolutely. Unfortunately we have much worse transgressions to deal
with, like people who refer to 700C tyres as 700mm. ;-)