RBT Projectors

[P3D Bob Aldridge <bob.aldridge@xxxxxx>]

Ther's been a bit of traffic recently about the RBT projector, so I
thought I'd post my experiences - both good and bad.

I've been working with these machines since the run up to the Eastbourne
ISU congress. As the Stereoscopic Society Projectionist, I got the job
of co-ordinating the projection side of things.

At this time, whilst very experienced with the Dual Hawk and having used
twin 2 x 2 projectors and the Bracket Disolver, I had virtually NO
experience of automatic twin projector dissolve set-ups! It soon became
obvious that we were going to have synchronising tracks of many
flavours. I had to learn fast!

Enter Don Wratten's Bassgen dissolve unit and RBT projector. I was able
to learn the basics from this equipment and some carousels and other
equipment from David Burder. I was lucky to also have Mike Fisher and
Colin Clay on the team.

Back to Don's RBT. It was wonderful to be able to show slide by remote
control. But the advance wasn't reliable. I studied the mechanism and
discovered that the slotted disk that indexed the position of the slide
tray was loose on its spindle. I fixed that with a 14BA screw (about as
thick as a pin!). 

At the Congress, RBT turned up with a loan of projectors and experienced
operators from Germany. I was able to leave the automatic "Realist
mount" shows to them - and it worked like a dream!

They also brought the Stereoscopic Society's own RBT with them. I am
lucky to be the custodian of this machine.

So I started using it at our monthly meetings and conventions. But one
machine is not enough. A member of the Stereoscopic Society, David
Robinson, gained the contract to produce a short automatic slide show
for a Countryside Centre on the South Coast of England. He asked me if I
would undertake the technical side of this installation.

He wanted to use a pair of RBT projectors, so I ordered these direct
from Franz Almendinger in at RBT in Germany, and collected them from the
HQ of RBT in Germany when they were ready. As part of my fee for the
technical services, I became the owner of a Bassgen synchroniser of my
own. In the back of my mind, I thought I might be able to use Don's
projector to make up the pair for dissolve shows.

Sadly, before I could do this, the Countryside Centre was destroyed by
fire. Of course, it was all insured, so it has been re-built, and again
I got the job of sorting out the installation. This time, I decided to
use my fee to acquire a projector of my own - so now I have a pair!

I like the projectors - they are very well built, but I have had some
problems. 

The slide advance has to be set up very accurately - particularly with
the Basgen controller that steps the magazines back to the start after a
show one slide at a time. Due to play in the gears, accurate positioning
of the tray in the forward direction can result in slides not dropping
in the reverse direction... I feel that the three projectors that I got
for the centre and myself had a poor batch of gears - one, certainly,
has worn prematurely. Fortunately, the projectors are "engineered" and I
can fit new parts, myself.

There have also been autofocus problems. When it works, this is
excellent. Sadly, my projector stopped working on one channel and went
back to Germany. It now works perfectly. Recently, the Stereoscopic
Society's machine has become unreliable on one channel. Franz has sent
me an uprated transistor for the circuit board, which I intend to fit
this weekend.

Other problems? Not that I can think of, and Franz is always very
helpful - on the phone... Faxes tend to get less urgent treatment. We
have to remember that this is a "Cottage Industry". There is very little
office back-up. 

I, for one, am very pleased that these projectors are available, at all.
They have given the "Realist" format mounts a new lease of life, and
make editing AV shows MUCH easier than with separate 2 x 2 mounts. 

And the RBT mounts are wonderful, as well! Used in conjunction with the
autofocussing projectors, you really don't need glass.

So what do you do with all those original glassed slides bound with
tape? Well, you DON'T trust the RBT to feed them automatically! Worth a
try, but seriously unreliable, in my experience.

So what DO you do with those collections of slides that are not in RBT
mounts? Well, I have evolved a system of hand feeding the slides whilst
the computer/control track on tape, controls the lamps and ejects the
old slides. It's a bit like feeding a toaster! I've automated Pat
Whitehous's famous "Tribute to Handel" this way, and I can use the
Bassgen controller to manually fade/feed the slides. The only problem
arising from this is the serious play in the horizontal and vertical
lens controls. You can't project a mixed set of slides such as you get
with "member's slides" - it's just not possible to take out the kind of
vertical errors that have given stereo a bad name in the past. I fall
back on the Dual Hawk in these situations.

So that's my 50 cents' worth.

Bob Aldridge
Stereoscopic Society Projectionist
---
 * POW 2.0  0007 * If at first you don't succeed, get a bigger hammer!


------------------------------