[Radium[_4_]]

On Jun 20, 9:14 am, peterh5322
wrote:
On 2007-06-20 03:33:41 -0700, Early Film said:

Different recording heads may produce different artifacts, but in many
cases the same head can record both VA and VD.

In one case the head is the same, the Maurer.

Now, the Western Electric RA-1231 used the same valve for VA as for VD,
but the valve's integral optical system was different, as one might
expect.

Also, the valve unit was different for 16mm as for 35mm, but the
principle was the same: same valve, 35/16mm; different optical systems:
35mm VA, 35mm VD, 16mm VA, 16mm VD; in one instantly interchangeable
unit.

The RA-1231 was a dual-gauge 35/16mm recorder, and was also the first
"Davis Loop" (AKA, "Davis tight loop") recorder.

The RA-1231 is easily the "exemplar" of all optical recorders. This
sixty-year-old machine is the basis of the Westrex/Nuoptix (now
Nuoptix/Photophone) stereo variable-area (S V-A) recorder, which, now,
records perhaps 99.44 percent of all optical tracks, produced
everywhere.

VD was abandoned primarily because of lab issues.

VA is now the de-facto standard not because of any presumed superiority
of VA over VD, but because 16mm is no longer an issue, in most cases,
and 35mm is now almost all stereo [ * ] , with the RA-1231's S V-A
valve being the only single-unit valve/optical system which is
implicitly time-aligned, and is eminently adaptable to stereo, two- or
four-channel.

[ * ] The RA-1231's dual-bilateral mono mode is simply a degenerate
case of its S V-A mode, but this fact was never fully appreciated by
industy researchers, although its capabilities were fully disclosed in
Frayne & Wolfe (1949), and elsewhere.


I strongly prefer VD over VA.