[LargeFormat] Ultrabiglargeformatcamera

[Richard Knoppow]

----- Original Message -----
From: "Jim Brick" <jbrick@elesys.net>
To: <largeformat@f32.net>
Sent: Wednesday, March 05, 2003 3:13 PM
Subject: Re: [LargeFormat] Ultrabiglargeformatcamera


> The camera is a process camera, used by the semiconductor
and printing
> industries for decades. I ran one of these in the early
60's. As process
> cameras go, this one is not particularly large. Those used
for making
> semiconductor masks make this one look like a toy.
>
> Process cameras for the printing industry used arc lamps
(later pulsed
> xenon lamps) and were used to make line and halftone
negatives.
>
> Process cameras for the semiconductor industry used a very
sharp cutoff
> green light and lenses that were made to be exceedingly
sharp only at that
> one wavelength. These cameras were made to be able to
reduce man made
> semiconductor layer tape-ups (very large) down to
microscopic size for
> masks from which to manufacture integrated circuits.
>
> The big process cameras were focused by the numbers. Not a
loupe and ground
> glass. A crank on the back to dial-in the number for the
percentage reduction.
>
> Jim
>
>
  Note the sprint shock mounts on the bed!
  The whole theory and practice of making half-tone plates
is fascinating. Its now almost a lost art, particularly the
original method using cross-screens made of ruled glass.
  The half-tone process was capable of very good quality
when done right but it more often was not. The average
quality of half-tone work done now is enormously better.
  Until the 1950's the medium of choice was wet plate
colloidion but it was rapidly displaced by self-screening
film which eliminated the need for the cross-screen and
special apertures. All done with computers and laser
printers now.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com