I majored in Multi-image slide presentation at RIT over 25 years ago. 
They had a core-curriculum in Multi-Image slide production, the only one 
like it in country at the time. I have produced many of these programs 
while at the college and at a production company where I worked for 
quite a few years after graduating.

There were three different manufacturers of multi-image slide 
programming equipment. AVL (on the west coast), Clearlight (on the east 
coast) and Multivision (I believe they were based in the mid-west - they 
were very short lived). AVL used "Procall" programming language, 
Clearlight used "Superstar", Multivision used "Show Pro"

All three used a computer with a proprietary programing code that fed 
data to dissolve units which controlled a projector's lamp and slide 
advance/reverse. As Richard points out below, they could also activate 
remote relays to turn on/off other items. The dissolve units were 
capable of anything from making the projector hard-cut the image on/off, 
to a slow 20 second dissolve or more. They could also freeze the 
dissolve at any point in time. Shows were usually aligned so that all 
the projectors in the same nest or "bank" were aligned perfectly onto 
the screen (most shows used animated sequences and graphics that were 
created using pin-registered computerized cameras such as a 
Marron-Carroll, Sickle (sp?) or Forox cameras). There could be as many 
as three individual banks in the case of a seamless widescreen show 
(called a "two screen butt-center overlap" - using slides that were 
masked at the appropriate edges to give a seamless look). I've seen as 
many as sixty projectors used for a widescreen show.

Slide projectors were most commonly mounted in special racks that held 
up to four projectors in a vertical rack known as a "stack". Chief was 
the most well known manufacturer of these special racks. Each projector 
in the rack had roll, tilt and yawl control so that all projectors in a 
stack could be perfectly aligned over the top of each other. Nests of 
multiple racks would then be positioned as close to each other as 
possible, sometimes using PC (perspective control) lenses to help with 
the alignment of many projectors that all needed to be positioned 
together in the same bank.

The most common reel to reel tape deck used would have been a 1/4" deck 
having four tracks/channels. Two tracks make up a stereo soundtrack, a 
third track would be a clock or timing track to link stereo audio track 
from the tape deck to the computer which controlled the projectors, and 
sometimes a fourth track that allowed for running the show without the 
computer (after you were done "programming" the show you could record 
the computer's output commands that would normally go to the dissolve 
units on the forth track so that you could leave the computer behind 
when traveling with the show). When listening to the programming track, 
it is clearly different to the clock or timing track. One is 
steady/cyclical whereas the other is totally random with many different 
frequency notes or tones.

The recreation of a multi-image slide presentation in digital format 
would be very tedious indeed. I am not currently aware of any slide 
scanning equipment which is pin registered - almost a must-have if you 
are looking to recreate a multi-image shows without having to re-align 
the slide images by hand in an NLE after they have been scanned. Most 
multi-image slide presentations used Wess brand three pin registered 
glass mounts. Because of the glass mounts, the images would have to be 
removed prior to scanning and removing each image from a Wess mount so 
it could be scanned would preclude any automated/batch slide scanner. 
Also, many multi-image programs had heavy use and travel. They got very 
dirty. Each slide would most likely need hand cleaning prior to 
scanning. Also many presentation had slides with Kodalith or similar 
gradation and holdback masks sandwiched with the image, further 
complicating the scanning process.

Outside of this is, is the faithful reproduction on the cadence and 
overlapping of the slides as they dissolved from one to the next on the 
screen. Multi-image shows were graceful and beautiful. Many programmers 
of these shows took great pride in how they programmed one dissolve to 
the next or an animated sequence of slides. I know, I used to program in 
all three computer languages and this was my main job at the production 
house where I worked. Without running the actual show and knowing the 
look that the person programming the show wanted to achieve, it would be 
little more than a guess as to what it really did look like, in all it's 
beauty and timing.

The companies that made both the computer programs and hardware for 
these programs have since long gone out of business. I still know of 
producers who have mothballed some of the old equipment to run them 
(both the computers/programming software and the dissolve units), but 
they have not run for quite some time and getting together everything 
needed to get a show up and running would be a real reach.

I have quite a few multi-image shows recorded to tape, including one 
that was produced by AVL to promote its programming software and 
hardware. If anyone is interested in seeing some examples of these 
shows, I'm happy to post some to Vimeo later in the week.

As a side note, all multi-image shows were a nail biting hand wringing 
experience when running the programs in pressure situations in front 
large audiences. There were tray jams, bulb burnouts, and equipment 
failures galore. Dove dissolve units and other equipment, that were 
promoted by AVL to be very reliable weren't always so. The Dove dissolve 
units for example had volatile RAM memory. A simple static charge could 
freeze up a dissolve unit into not knowing what it was or what it had to 
do. Such was the case when I was staging a 21 projector show in a 
ballroom at Bally's in Vegas. The static charge from the carpet kept 
wiping out the Dove dissolve's memory and we never able to get the show 
running. It was budgeted at $350.000 and we were trying to run in front 
of a crowd of 1200 employees for a new product release. The client was 
fit to be tied. A terrible night. In the instructions for clearing a 
Dove's RAM memory - one of the solutions in the manual was to pick the 
unit 3-4 inches off the table and drop it back on the table!


John Schroth
Media Transfer Service, LLC

On 8/5/2012 12:49 PM, Richard L. Hess wrote:
> Hi, Randy and Michael,
> I guess 6K is enough resolution, but the TIFs I have of each 35 mm 
> slide are approx 36 MB each. 3000 x 4500 (minus some cropping) pixels 
> @ 3000 ppi. You can't put too many of those into FCP, can you? They 
> certainly crashed Premiere a while ago.
> Also, as a side note, top-quality Kodachrome and Fuji Velvia 35 mm 
> slides are more faithfully captured at 4000 x 6000 pixels, 16 
> bits/colour, making approximately 144 MB TIF files per image. Frankly, 
> very few of the images I'm scanning can truly benefit from this 
> increased scan detail, but some can. It seems that audio-visual 
> materials are held in sound archives. I have transferred a few 
> cassette tapes with simple "beep" tones on track 4.
> The issue with resolution is that if each slide can benefit from 3000 
> x 4500 pixel scans, and you've got a 4x4 grid you need 6000 x 9000 so 
> as to not lose resolution, or in the 3-wide display, 3000 x 13,500 and 
> that does not take into account vertical images.
> I realize we did not achieve that resolution with typical Kodak 
> Carousel zoom lenses, even with autofocus.
> Ingesting the elements is not a challenge, but having attempted it at 
> high resolution a while ago, assembly IS a challenge. Retaining the 
> IMPACT of the original show is the challenge. Reference copies are not 
> a challenge (though still tedious).
> As to Mike Biel's point, the cue tracks that he describe were, I 
> believe, proprietary formats per manufacturer. AVL was the name that 
> came to mind, but they are now gone. At one point, their controllers 
> would record all the cues on the audio tape. The later units, 
> described here from
> , merely had a time code 
> track on the tape.
> <quote>
> The first Eagle computers were produced by Audio Visual Labs (AVL 
> <>), a company founded by Chuck 
> Kappenman in New Jersey in the early 1970s to produce proprietary 
> large-formatmulti-image 
> <>equipment. Kappenman 
> introduced the world's first microprocessor-controlled multi-image 
> programming computers, the ShowPro III and V, which were dedicated 
> controllers. In 1980, AVL introduced the first non-dedicated 
> controller, the Eagle. This first Eagle computer utilized a 16 kHz 
> processor and had a 5-inch disk drive for online storage.
> The Eagle ran PROCALL 
> (/PRO/grammable/C/omputer/A/udio-visual/L/anguage/L/ibrary) software 
> for writing cues to control up to 30Ektagraphic projectors 
> <>, five16 mm 
> film <>projectors and 20 
> auxiliary control points. Digital control data was sourced via anRCA 
> <>orXLR 
> <>-type audio connector at the rear of 
> the unit. AVL's proprietary "ClockTrak" (a biphase digitaltimecode 
> <>similar to, but incompatible 
> withSMPTE <>timecode) was sourced 
> from the control channel of amultitrack 
> <>analog audio tape 
> deck. The timed list of events in the Eagle was synchronized to the 
> ClockTrak. Later versions of PROCALL included the option of using 
> SMPTE timecode. Most programmers abandoned ClockTrak for SMPTE, as 
> more multi-image programs began to incorporatevideo 
> <>.^[1] 
> <>
> Two separate digital data streams were output from the Eagle, also via 
> RCA or XLR-type audio connectors. These telemetry streams, called 
> "PosiTrak", each controlled up to five external slide projector 
> control devices also manufactured by AVL, known as "Doves". The Dove 
> units received biphase data from the Eagle via audio cables, and 
> interpreted the Eagle's data streams to control as many as threeKodak 
> Ektagraphic projectors 
> <>(for large 
> screens, compatibleXenon 
> <>-lamped projectors) and 
> two dry-closure contacts per Dove unit. AVL also made the Raven, a 
> device similar to the Dove, for comprehensive control of a single 16 
> mm film projector, as well as numerous other external control devices 
> for lighting, sound, video projectors and sources, etc.
> AVL Eagles and associated products, when properly setup and powered, 
> were extremely reliable. During the 1970s through the early 1990s, 
> when the products of its competitors were not as reliable nor readily 
> available, AVL became the industry standard for multi-image control 
> equipment. However, the development of large-screen electronic media 
> andHDTV <>ushered out the era of 
> film-based multi-image productions.^[2] 
> <>
> </quote>
> The first footnoted link is:
> The second one is 404 gone, like the technology, but the text (but 
> sadly not the images) is available here
> Cheers,
> Richard