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35mm stuff

AV History


Audio Visual Laboratories (AVL) was based in Phoenix Arizona, USA and produced probably the most commonly used audio-visual control systems used during the 1980's. They certainly dominated the North American and European markets.

Primarily a microprocessor based control system to control multiple 35mm carousel slide projectors for exhibition and conference use. This was the technique used before the advent of Microsoft Windows or the Apple Macintosh (and hence-forth MS PowerPoint and other presentation software) to present visual information to small and large audiences at conferences and product launches.

The AVL control systems developed from the late 1970's from solid-state controls with lots of buttons, through to PC-M based desktop computers (the Eagle) through to the IBM-PC based Genesis running MS-DOS. Code was typed into a command line style prompt that generated an audio signal from the special on-board card that sent a signal to a controller known as a Dove that in turn controlled three carousel slide projectors. Up to ten Doves could be connected to one computer, thus a maximum of thirty slide projectors could the independently controlled - dissolving the lamp up and down at a variety of rates and stepping the projector forwards, backwards, or not at all.

AVL Procall screen shot

How was all this done?
Two dimensional artwork was created on paper, usually in black and white. This was photographed on positive of negative film, often to a complex grid, which was then re photographed using coloured filters on to 35mm slide film to create just part of the finished image. Two, three or more slide projectors would then project different parts of the image to create the overall whole. All the images had to accurately photographed using specialist pin-register cameras (typically the Forox), then mounted in special pin-registered slide mounts (typically Wess), loaded into precision carousel slide projectors (typically Kodak) and then programmed using a projection control system (typically AVL). Today, mind boggling complex but the normal way of doing things during the 1980's.

AVL and ebay
From time to time old bits of AVL kit turn up on auction sites like ebay and because I have one of the few web sites that refer to AVL, I get asked the questions about what's on offer/has be bought. I would rather not, thank you. The stuff is about 20-years old and was often designed to only work as part of a system. If you come across a Dove dissolve unit, you can attach a hand control and use it to cycle between two or three compatible projectors, but you will not be able to automate the process without a programming unit.

23 May, 2006

© Nigel Sadler 1995-2008

anti-spam email: nigel at herriott-sadler dot co dot uk
Location: Forest Row, East Sussex, England

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