[Leica]Format units question (long)

[Frank Dernie <FrankDernie@compuserve.com>]

Hi everybody.

I am an English engineer who has practiced my profession in Imperial and =
SI
(Systeme International) units. I find the SI system more convenient
although clearly the easiest units for a technician to deal with are thos=
e
his machine is calibrated for! any alternative requires calculations. I
well remember the mistakes made during the transition period! one of the
most amusing was when a young technician from the prototype shop came up =
to
the drawing office to ask one of the (older) designers how to split a cla=
mp
collar he had made. The designer was expecting an elaborate piece about 1=
=2E5
inches dia. He got an impressively made 1.5 mm piece of expensive
scrap......
As a matter of interest the cm does not strictly exist as an approved uni=
t
as the SI system recommends relationships of 1000 (pico, nano, micro,
milli, kilo, mega etc.)
Also in England "thou" is the normal shorthand for 0.001 inches, "mil" is=

the normal shortening of millimeter, another opportunity for confusion in=

translation from English to American!
The Farenheit scale may be familiar to many but is a story of scientific
innacuracy in the old days. Farenheit also chose 0 and 100 as his fixed
points, but in this case he chose the coldest thing he knew as 0 (frozen
seawater) and normal human temperature as 100. The first varied depending=

on salinity and weather and he merely measured the other wrong! On the
other hand any old units can work once you get used to them.
My pet hate is the date system used in the world Tje Japanese system of
year/month/day seems logical (like a clock) there is some logic in the
european system of day/month/year. There is not a vestige of logic in the=

US system of month/day/year....total confusion!

Back on subject my Leica has 21,24,35,50,75 and 90mm lenses on 24x36mm
negatives but I print on 10x8 and 12x16 Cibacrome :) though the packet is=

marked in cm..

Frank