2001-06-17
Hmmm. Wouldn't the difference be 0.2 mm? 35 - 34.8 = 0.2. But, anyways. I
agree with you. How can anyone tell the difference between the two? Who is
to say that the American companies like Kodak or Polaroid didn't use the FFU
size and everyone else used 35 mm? I can't see where 200 �m would make a
difference. I can't see how anyone can measure the media with a instrument
without distorting it. I can imagine the material compressing slightly
under test to give the false impression it is < 35 mm.
Also, if you convert 1-3/8 to decimal, it becomes 1.375. Multiply this by
25.4 and you get 34.925, a difference of 0.075 mm (This is the number you
really meant, isn't it Jim?). 1.37 multiplied by 25.4 is 34.798 (which is
where the 34.8 comes from) and 1.38 by 25.4 is 35.052. So, in reality it
depends on what decimal inch value one rounds to as to what it comes out in
millimetres. Maybe for this reason, the engineers of yesteryear figured 35
mm was good enough for all.
Maybe the people on these websites must have assumed the size was 1-3/8 in
as the closest to 35 mm in fractional form and assumed that it started out
as an inch standard and was later converted to metric as 35 mm. They took
the exact 35 mm back converted it to FFU and rounded it to the nearest
fraction, then back converted it to millimetres by rounding 3/8 first to two
decimal places by truncating. If they rounded up instead of rounding down,
they would get 35 mm exactly.
Even the half size mentioned is 17,5 mm and not 17.4, which would be half of
34.8.
The only way to know for sure is to ask someone directly involved in making
film.
John
Keiner ist hoffnungsloser versklavt als derjenige, der irrt�mlich glaubt
frei zu sein.
There are none more hopelessly enslaved then those who falsely believe they
are free!
Johann Wolfgang von Goethe (1749-1832)
----- Original Message -----
From: "James R. Frysinger" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[EMAIL PROTECTED]>
Sent: Saturday, 2001-06-16 20:10
Subject: [USMA:13829] Re: Fw: Questions about measurement standards
> The difference in the sizes metioned amounts to 0.75 mm. Could some of
> that be due to allowance for thermal expansion or for kerfing losses of
> some sort? (Even if cut by knife, there might be some smoothing that is
> done which would reduce the width.)
>
> Jim
>
> On Saturday 16 June 2001 1930, Joseph B. Reid wrote:
> > I am grateful to Bill Potts for the additional information he found
> > in USMA 13826
> ....
> > >There's an interesting page at
> > > http://www.subclub.org/shop/halframe.htm, in which the author notes
> > > that 35 mm film is actually 34.8 mm, and that it is, in fact,
> > > 1-3/8" wide. I have checked and he is right.
> >
> > The Lumi�re brothers were the first to present a public performance
> > of motion pictures. I have visited the room on the Rive Gauche in
> > Paris where the show took place. If the film is only 1-3/8" wide it
> > is a modification due to (American) Society of Motion Picture
> > Engineers. I started my professional career with Kodak Limited,
> > Harrow, Middlesex, and I never heard a suggestion that 35 mm was
> > really 1-3/8". It is unlikely that Agfa would produce 1-3/8" film
> > and call it 35 mm. Also, if SMPE shaved down the width of the f9m,
> > why did they preserve the metric sprocket spacing and the metric
> > frame size? I suspect that American engineers may have referred to
> > the film as 1-3/8" as a measurement that Americans could understand,
> > but that it was really 35 mm.
> ....
> --
> James R. Frysinger University/College of Charleston
> 10 Captiva Row Dept. of Physics and Astronomy
> Charleston, SC 29407 66 George Street
> 843.225.0805 Charleston, SC 29424
> http://www.cofc.edu/~frysingj [EMAIL PROTECTED]
> Cert. Adv. Metrication Specialist 843.953.7644
>
