Multi-projector slide shows are worth the effort for several reasons: They avoid eye fatigue by not going from bright slides to black to bright to black, and they look a whole lot more professional.
In order to do a multi-projector slide show, you need, at a minimum:
There are other things you may want:
Many companies have manufactured dissolves, but there are only a few left. In the US, Arion, ClearLight, Entre, Gemini, and Klad are current manufacturers. RMF dissolves are made by Klad and Kodak dissolves are made by Arion.
Dissolves vary in features. Here are some examples:
Dissolves are available to run anything from one projector to at least six, and some models can be ganged to run thirty or more projectors.
Some dissolves can be run by pressing buttons, others by turning a knob or moving a lever, and some are controlled by typing at a computer.
Some allow the projectors to be run independently, so you can superimpose one slide over another (useful for titles) or do special effects.
Dissolves may be programmable, that is they can be run from an audio signal which can be on a tape. Some of these can program, that is they can generate the audio signal. Some have no buttons and can only play back from a tape. Some are programmers only, and require a playback unit to actually control the projectors.
Some dissolves keep track of the slide position of each projector. And some generate a special audio signal which contains the slide position of each projector all the time.
Some dissolves check the bulb and notice if it has died.
Some are programmed in "real time", that is you move the controls as the show is going. Others are "leisure time" programmable, in which case you set the dissolve rates and possibly the timings in advance.
Some dissolves have a timer, which automatically fades to the next slide after a specified time.
All of these features, except leisure time programming are readily available in two projector dissolves. Leisure time is common in three projector systems and beyond, and I wouldn't want to try to program a three projector show in real time.
I'm assuming most people are interested in two projector dissolves, both because they are simpler and because two projector systems cost less than larger systems. Here's what you get as you move from the simplest to the most powerful dissolves:
The simplest dissolves have one button. You press it and one projector fades down and the other fades up.
Many of these are not programmable. Some offer a bit more control over the dissolve rate. Here are a few examples:
Kodak made one. It had one button which caused a 1 1/2 second fade. It was programmable only to the extent that if it received a 1000 Hz audio tone it would fade as though the button was pressed.
Arion sells the Mirage 101 and 201. The 101 has three buttons, "Fast", "Medium", and "Slow". The 201 has five rates as well as a timer.
RMF sells the Model 300 Image Blender. It has one button which advances the projector and a control that sets the fade time. It also has a timer. It can be programmed through a 1000 Hz audio tone, and it has a tone generator so it can make the tone.
As far as I know, Entre is the only manufacturer of analog dissolves still in business. The low end units, such as the 7605 and 7610, have a single control, either a slide or knob. You turn or slide the control to the left to brighten one projector and darken the other, and to the right for the reverse. If you move the control all the way to one end the dark projector advances.
Higher end units offer a pushbutton control, timers, and have the capability of running up to six projectors.
All of the units are programmable and generate the necessary audio signal.
I've seen quite a few shows using analog dissolves. The thing I don't like about them is that many people don't get smooth or consistent fades. And the two projector dissolves are not capable of special effects such as superimposition, where both projector lamps are at full brightness.
If you use one of these I suggest you get a stopwatch, (a digital wristwatch will do) and practice making smooth consistent two second dissolves. This can make the difference, at least to me, between something that looks professional and something that looks like it was thrown together.
And if you have one with the tiny remote control, you can make it easier to handle by bolting it to something a bit bigger and replacing the knob with a larger one. Personally, I'd rather have the slide control.
The next step up are the digital dissolves. At a minimum, they have a choice of dissolve rates which are controlled by a computer and are therefore always smooth and consistent.
All of these are programmable. Their programming signals are complex and contain digital information, encoded somewhat like the way a modem encodes signals to send them over telephone lines. For some of these units the signal includes the tray positions, which makes setting up a program using synchronized music much easier:
Arion has two units, the Mirage 701 and 901. Both use Mate-trac(TM) which is Arion's name for a method of encoding the slide tray positions in the audio signal. The 701 has five dissolve rates and a timer. The 901 adds individual projector lamp control for superimpositions and effects as well as another dissolve rate. These units are also sold under the Kodak name.
Clearlight sells the Star Programmer 2, or SP2. It uses QS/20, which is Clearlight's method of encoding tray position information. It keeps track of the tray position and monitor the lamps in case one burns out. They also detect when a tray advance fails and I've seen one fight a projector with a bad clutch and win most of the time.
Klad sells the Wizard. It has individual projector lamp control and a timer. It uses Autolock, which is Klad's name for an encoding of tray locations. This unit is also sold as the RMF wizard.
Gemini Electronics sells the Gemini 2000 two projector dissolve. It has Sync-Lock, which is their name for tray position encoding.
I did not note it, but some digital dissolves can also run off a standard projector remote control.
Arion, Clearlight, Entre, and Klad all make dissolve equipment for three or more projectors. Some of these, such as Clearlight's MP3 are three projector dissolves in one box, like the two projector dissolves but with some leisure time capabilities.
Arion also has a new system, the Arion Show Wizard. It is programmed on a PC using a USB interface. Programs, including the audio files, can be stored on compact flash cards. This is the most modern system I know of from a U.S. manufacturer.
Beyond that, Arion, Clearlight, Gemini, and Klad make systems which are capable of programming lots of projectors. These use a separate programmer, possibly attached to a computer, and one or more playback dissolves. Several European companies make this type of equipment as well.
Most projectors have a remote connector which is compatible with the Kodak Ektagraphic. There are five pins on the remote, but the projector actually has a socket for seven pins - there are two more next to the remote connector. Leica, Singer/Telex, Elmo, and others use this same system on some of their projectors, and most dissolves will work with them. There are some exceptions though - I had an old Singer Caramate which would not work with my dissolve because the voltage levels were different.
There are other projectors which are not compatible, such as the Kodak Ektapro and S-AV, and there are dissolve units built specially for these projectors. Also some projectors use very high powered lamps that require a special interface to work with most dissolves. And some dissolve can not handle the current requirements of the older Carousel projectors which used 500 watt non-halogen lamps, such as the Carousel 650 and 760 (the 650h and 760h are halogen and are OK).
AVL has left the business. As far as I know, new equipment is unavailable. Repairs are available from John Nelson, Audio Visual Repair, 1200 Reservoir Rd Cheshire, CT 06410. Telephone (203) 272-5145 or (800) 223-0213.
Klad does not have a web page but RMF does. I've also seen RMF dissolves for sale mail-order from Markertek Video Supply, 800-522-2025. And RMF sells direct at camera club shows, such as the New England Camera Club Council Convention.
Clearlight is manufactured and serviced by Boltronics. However you can get better prices from a dealer.
Arion dissappeared without a trace. I do not know how to contact them..
Entre does not have a web site but their phone number is 503-649-4641 and their address is 2184 SE 53rd Avenue, Suite 200, Hillsboro, OR 97123-7800. Their equipment is also available through several mail-order stores in New York.
Gemini Electronics has a website and their phone number is 650-347-3619.
There are several European manufacturers. Dataton and AV Stumpfl sell high end equipment. I do not know if they still sell new dissolve units, though.
A lot of equipment is available used. Several dealers and occasionally individuals advertise dissolves in Shutterbug magazine. There have been a number of dissolves on the eBay auction site as well. Among the better two projector models which have been for sale recently are the Clearlight Micro-Diamond MD-D and the Kodak Ektagraphic Dissolve series.
There are also a lot of companies which used to make dissolves which either are out of the business or are not in any catalog I have. If they work these can be good values. From things I've read Electrosonics, Imatronic, Mackenzie Labs, Muewo, Rollei, Sinda, Spindler, Tiffen, and Wollensack make or made dissolves. I'm sure there are others. Many of them are simple analog units and should be inexpensive. However you take a risk with such a dissolve because if it breaks it may not be possible to repair it.
Note that some Wollensack dissolves were actually made by Arion.
I have a few loaner dissolves (if you live in Massachusetts or thereabouts and want to borrow one, get in touch with me).
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Last modified 22 July 2009