MAKING A START WITH AUDIO-VISUAL
Part One - The Equipment

Audio-Visual presentations tend to bring gasps of pleasure from your audience, even if the quality of your photography is not as brilliant as it might be! It seems that the slide change from one to the next, because it is a dissolve from one image to the other, coupled with appropriate music and/or effects plus a sensible commentary creates an air of professionalism which otherwise might be lacking.

            So how do we go about imparting such an effect with our slide shows? For starters we need two projectors, preferably with matched light outputs and lenses, a dissolve unit which can be manual but more usually is nowadays electronic and some means of sound reproduction.

            You almost certainly have one projector already, but if it is a bit long in the tooth or showing signs of wear, you might want to pamper yourself for this new year and get either a matched pair, or, if you have deep, bulging pockets a two in one machine. Let’s take the latter first — the only make I know of still available is that of Rollei. These start at £899 and go upwards to over £1500 (lenses extra!) so can I assume that you have lost interest in that particular brand? Or have you won the lottery lately?

            Therefore we can move on to two single units. There aren’t many on the market these days, so I’ll stick my neck out and recommend a brand that should be available from any photographic shop (albeit to special order). The German firm of Braun, strictly speaking pronounced Brown, rather than that which replaces brain, has been manufacturing slide projectors for nearly half a century. They should have learned a thing or two in that time! The best series they make come under the Paximat Multimag label. As the name suggests, these projectors accept a variety of different slide magazines. Six types to be precise, including the ubiquitous “Universal” which many users already have their slides in — giving an otherwise unsuspected saving. Model 250AFI has the benefit of auto focus with the more powerful 24 volt 250 watt IQ lamp (A1/223) costing less than £3 to replace. Braun give a two year warranty as well which is quite refreshing these days.

            The projector comes with the standard 85mm prime lens, multi-coated of course with an f/2.8 aperture and ideal for normal sized rooms. Cost for this model is £199.99 so if you need two rather than just adding another to the one you already have, just double the number you first thought of! Long focal length lenses, including a 70 - 120mm zoom, are made especially for use in halls or very large rooms. These include a high performance standard lens, 90mm f/2.5, the 70 - 120 zoom already mentioned, and a 150mm f/3. There are other zooms such as 85 - 150mm f/4 and 110 - 200mm f/3.5 which can be bought separately too.

            If you are not sure which you would require the chart may be of help. It shows the width ‘c’ of the projected image at different projection distances ‘b’ based on the usual 24mm x 36mm slide. The angle of projection ‘a’ and the various focal lengths are indicated in red.

            Both projectors need to be firmly mounted on suitable stand(s), so that the images on the screen can be superimposed without fear of unwanted movement. Those whose woodworking skills approach genius level (compared with mine that is!) can fairly easily knock up something which will be sufficiently rigid. For the rest of us there are two ready made types of stand from the projector makers.

            The first, called the Paximat Multimag AV projection rack, is a projection stand to be placed on a table. For undistorted pictures in overlap dissolve projection it is useful and advisable to place the two projectors above each other so that the optical axes lie very close together.

            The AV Rack has two platforms which can be tilted by 5° upwards and downwards. Thus it is possible to project almost without any distortion of the pictures even at close quarters. The platforms are adjustable in height so that circular magazines can be used. Below the tables there is enough space for accessories. Size of the projection tables is roughly 46 x 36cm., the whole rack has a size of 50 x 37.5 x 45cm and the four feet are adjustable for even balance. These details should enable the master joiners to make their own fairly easily.

            The second is a freestanding affair, called the Paximat Multimag AV Projection Stand. There are three platforms, the top one tilting 5° upwards and downwards while the bottom two may be placed in any one of six positions. Further platforms could be added if required. Two roller feet enable easy moving, while two adjustabe feet with fixing nuts ensure firm stability.

            We have to consider now the method of cross fading the two projectors. Many years ago I used a friend’s Pollock Fader. Made by George Pollock this was totally manual, consisting of a large board to take the two projectors side by side with two fully closing irises operated by cable releases. Very reliable in use but very wearing on both nerves and memory, especially if slides had to be matched to the rhythm of a particular piece of music.

            Things are much easier these days. There are no less than four different accessories for such work made by Braun for the Paximat range. These dissolve units are called respectively, Paximat Multimag Duo 66, Paximat Multimag Duo A 350, Paximat Multimag Duo A 655 and Paximat Multimag Duo A 6000. Then for the aforementioned lottery winners there is the pièce de resistance, the Paximat Multimag PXD 8000 PC-Slide Show using your computer to control up to 8 projectors giving effects to blow your mind! Coming down to earth, I’ll briefly run through the first four. 

The Paximat Multimag Duo 66 is extremely easy to operate. It allows manual dissolve control between the pictures during projection. You can directly connect the Duo 66 to two slide projectors. A modern Pollock system without the board, the irises and the cable releases and much smaller, but apart from that pretty much the same!

            Moving up the automatic scale somewhat we come to the next dissolve unit. Known as the Paximat Multimag Duo A 350 this is an overlap dissolve unit with a large number of controlling facilities.

            The slide show can run automatically with slides changing at intervals varying from approximately 3 to 99 seconds pre-set precisely with a large built-in LED indicator.

            With the aid of two rotating knobs the fade-in and fade-out phases for the two projectors can be pre-set between about two and fifteen seconds. Manual dissolves are also catered for for those suffering Pollock withdrawal symptoms. If you want to add sound and have it run automatically with the slide changing you need a pulse unit and a cassette recorder which allows recording pulses on the tape. These pulses then control the whole show on playback.

            Going on one stage further we come to the Paximat Multimag Duo A 655. This is similar to the A 350 but has a built-in pulse generator. With two buttons you control the forward and reverse changing of your slides. Lap dissolves follow directly in pre-arranged sequence. The duration of the cross fade can be set by means of 5 buttons for 0, 2, 4, 8 or 18 seconds. Two diodes, labelled A and B, indicate which projector is providing the image on screen. A cassette recorder with built-in pulse head can receive the pulses provided by the A 655 as well as all information and effects for slide changing. This is probably the ideal unit of the four for producing an overlap dissolve slide show as it requires virtually no previous experience in the technique.

            Finally, we come to the Paximat Multimag Duo A 6000, which has all functions controlled by the latest microprocessor technology. Large LED indicators keep you informed of the actual

position of the projected slides. Two projectors can be controlled manually and a sound accompanied slide show canbe recorded on tape and replayed. The position of the magazine and brightness are automatically coded and registered on tape. At replay the dissolve unit compares the coded with the actual position of the magazine and, if necessary, automatically carries out any corrections. There are seven dissolve times from ‘cut’ up to sixteen seconds. Dissolves can be carried out selectively with or without subsequent slide change of the non-projecting machine.

            A summary of the units for direct comparison follows:

 

Editorial

CRCMain