Here we will examine how we might arrive at owning an up-to-date slide projector for the more popular 35mm stereo formats - Realist and 2"x2".  We will consider two ways of doing this.

 1. Modifying projectors from the 1950's and a bit later.

 2. Building projectors from modern 'donors'

The examples referred to in this project are ones of which I have personal experience.  The information that I have provided is on the understanding that the detail provided may not match the projector that you may be intending to work on.

Modifiying Projectors 

Although the projectors built during the 1950's were excellent in terms of mechanical design, the light sources available at the time where significantly less efficient than those found in later, mono projectors.  Early projector lamps were based on the same technology as domestic lighting, usually working at mains voltage and emitting lots of heat relative to their luminescence.  In comparison, modern day projectors, in the main, use low voltage light sources running at a high current rating with much smaller filaments burning in halogen gas. 

The earlier lamps are becoming scarce and consequently the cost is high - may be up to £30 each.  Modern lamps are readily available and cost as little as £3.  A modern day lamp of say 24 volt - 150 watts is significantly brighter than most lamps used in early projectors and is sufficient for projection in the home or small hall.  A 24 volt - 250 watt lamp is sufficient for most occasions and are commonplace in many of the modern projectors used for industrial presentations such as the Kodak 2000 series.

Our main purpose here then will be to address the issues surrounding lamp upgrades along with the electrical, optical and cooling aspects of the project.

I have chosen to use three examples.  The first being a Bamag projector ,Figure 1. manufactured in West Germany the early 1950's, the second being a FED projector, Figure 2. built in the Ukraine during the 1980's.  My last example is a recently acquired Hawk I projector, not yet completed.

Building Projectors 

Many modern slide projectors are becoming available at low cost, this is due in part to the recent move towards the use computer based presentations and the availability of Video projectors.  The preparation and control of multi-projector, corporate presentations is much easier with Video projectors than with the film slide based Kodak carousel projectors.  Serious photographers will of course stick with film based projectors, that is until the quality of the digital projector reaches the standard of the digital camera.

Any slide projector built during the last fifteen years or so is eligible as a donor for the building of a stereo projector.  I chose to use two Leitz P150's for my first DIY projector - the Aldous/Leitz Figure 3.  This turned out to be both expensive and thwart with difficulties but, thanks to B&Q and a little ingenuity, I now have a very Cool, Compact and Quiet stereo projector which has become a benchmark for my other projects of this kind and has provided me with background of knowledge for the future.

My next stereo projector will be based on two Kodak 2000 series projectors.  This choice being for the aforementioned reasons.  I have been fortunate to pick-up half a dozen Kodak's with 70mm-120mm zoom lenses for less than £100 the lot!.  More on this later, for now, we will stick with the learning curve using the two Leitz machines.

Barry Aldous - Novemeber 2004

Click on Image to enlarge

Figure 1.

Figure 2.

Figure 3.