Re: Different Formats for Different Countries -- Variable Density B&W Film

"David Nebenzahl"  wrote

> "Metric sizes" are film sizes normally stated in, well, metric measures,
> like 6x9 and 9x12 (both in centimeters), as opposed to "inch"-sized
> films, like 4x5, 5x7, 8x10, etc. So, counterintuitively, 9x12 film is
> smaller than 4x5 film.

    Except metric film sizes aren't exactly what they say they are. The
frame size of a 120 film tends to be not 6cm wide but about 5.8 cm, with
120
film being about 62mm across. The other variations likwise are a bit
smaller
than the nominal size. It allows a bit of masking in the film holder of
the
enlarger, but nevertheless is not as precise as metricists might like you
to
believe. I could claim that the pinhole camera I'm currently ba****ng from
a
Kodak Brownie 2A is a "6x12" because it works by winding through alternate
frame numbers down the middle of the film (where the 6x6 numbers go) but
the
actual image size is 54 x 108mm, being the old Kodak 116 film gate with a
strip of brass soldered each side to provide edge sup****t for the slightly
smaller 120 film. It'll be printed using a 5 x 4 imperial enlarger (DeVere
54) with a black card mask over the neg gl***** to minimise Callier flare
from the edges.

    Of course 9 x 12 is smaller than 4 x 5! Those of us used to dealing in
metric know that 4 x 5 is 10 x 12.5cm - are at least it should be: if
that's
the sheet film size then image size will be smaller because of the little
edge-retains in the film holder.

    Someone on a forum - possibly not this one - confused me recently by
saying that "full plate" was 8 x 6 inches and all else was a division of
that. Sounds like the confusion over book binding classifications based on
a
broadsheet being 15" x 20" except when it wasn't. I thought "full plate"
was
10 x 8 inches, as the original master size for photos and respected to
this
day in paper sizes. Am I wrong?

    Tony Clarke