When I first heard that Kodak was discontinuing the manufacture of their carousel slide projectors, I immediately likened the news to the sad demise of the vinyl LP record. Yet it didn't take long for fond reminiscences to turn cold. The state-of-the-art successor to the classic celluloid still-frame projector, unlike the compact disc, still suffers from quite the inferiority complex. Yes, the video/data projector is great and has its place, but is still no match for the Ektagraphic in at least two little areas: resolution and footcandles per dollar. While only people equipped with bat's ears can hear the digital stepping of a 16-bit, 44.1 kHz CD's waveform, practically everyone can clearly see the projected pixels from a video/data projector at any reasonable viewing distance.
This seems like a serious concern, especially when you consider the burgeoning appeal of projection design in live theatre. Granted, maybe it isn't such a problem for-some of the big-budget shows we read about here in Entertainment Design, but for the rest of us, creating theatre in faraway places, where the state population is less than any of the six largest US cities, the thought of life without Kodak is tantamount to eliminating any possibility of a projection design. Even if I'm overreacting, it's simple math to figure out that when parts are no longer made, an ending is eventually inevitable. If Kodak's competitors bow and follow suit, we could even be looking at the end of 35mm slides entirely.
Of course, when you spend your entire career working in theatres located at the fringe of society, you learn to stick with what works best: creativity in the face of seeming impossibility. So I began to think what I could use when and if the fated day finally arrives and slides are no longer easy. The standard overhead projector (as opposed to any projector hanging from the ceiling) is often bypassed and probably much maligned by most projection designers, but is a valuable tool which deserves to see much greater use in projection design for live theatre, particularly in theatres that-can't afford the latest and greatest. And they're still being manufactured.
Before I go any further, I need to post a disclaimer. I am not a projection designer, nor do I claim expertise. I'm one of those technical directors at a small liberal arts college who is charged with knowing a little about everything. I have no access to big budgets, corporate sponsorships, or nearby experts offering free advice. When I need to project something, I have to rely on whatever I can to get the job done. Since I know there are many like me, I write on.
The safest way to justify the overhead projector as a valuable tool is to back it up with some numbers. Since manufacturers don't report light output in a way suited to live theatre, I conducted a photometric test to see how well an overhead would hold up to a slide projector and an LCD video/data projector. For my test, I used an Eiki overhead projector model #3895BP with an EVD 36v/400W lamp switched to the high setting. The slide projector was Kodak's Ektagraphic III AMT outfitted with a 100-150mm f/3.5 zoom lens (opened full wide) and an EXR-5 86V/300W lamp also switched to high. For the LCD projector, I used a Sony VPL-PX21 which featured a 1.3 × 1:1.7-2.1 zoom lens (also opened full wide) and Sony's specified lamp, product number LMP-P260, rated at 265W. My light meter was made by Sper Scientific Inc. (model #840021). Why did I choose this specific list of equipment? Because it's what I could get my hands on. It also rings truest to my whole point in writing this article. For many of us, we know that there are plenty of alternate solutions to image projection, but access to those solutions is often out of the question.
The overhead projected a 10' × 10' image at a throw distance of 15' and the light at the center of the field measured 51 footcandles. To achieve the same size field with the carousel required a throw of 24', reducing its light output to 27 footcandles. The field from the LCD projector is rectangular, but to give it the benefit of the doubt, I measured its output based on field width. At a distance of just under 19', its 10' wide field weighed in at 28 footcandles. This clearly shows that an overhead projector is able to hold its own in the realm of intensity and that it requires a shorter throw to produce a wider image. Interestingly enough, it still held up when all of the distances were equal. At a distance of 15', the slide projector brightened up to 68 footcandles and the LCD only improved to 44.
For those of you keeping score at home, the list price for the Eiki is $495. The Kodak lists at $950 (with lens), and Sony's VPL-PX40 (a replacement for the VPL-PX21) lists at $7,500. This can be loosely converted into a rough measure of footcandles per dollar with the Eiki being the clear winner at 22 footcandles per dollar. The slide projector delivers 15 footcandles per dollar, and the video/data projector sheepishly supplies just over one footcandle per dollar.
Another fairly scientific comparison between the three devices was made with a decibel meter held 12" away from the direct output of the exhaust fans. The overhead at 67 dB and the LCD at 68 dB were a good bit quieter than the slide projector's 74 dB. Remember that 74 is approximately five times louder than 67 decibels.
But there's more to my case that the overhead projector deserves respect than brightness, image size, affordability, and quietness. Practically anything can be projected, regardless of transparency or opacity — even three dimensional objects. Heat damage is hardly an issue. Since the projection surface is usually horizontal, master images don't need to account for gravity and can include liquids (just take precaution to make sure that liquids are kept safely away from any electricity). If slide-like photorealism or computer-manipulated imagery is desired, anyplace with a color laser copier or printer can print to full-color, blank transparency sheets.
Perhaps best of all, overhead projections can be manipulated by hand while being cast. This image can be controlled by projectionists, puppeteers, or a performer interacting with whatever else is happening onstage. Hand-drawn rough-drafts can be drawn in the theatre space to accurately compensate for distortion from oblique projection angles. Likewise, because of such easy access to the image both before and after it passes through the projection lens, fun possibilities are practically limitless. I once saw the Omaha Magic Theatre (featuring notable playwright Megan Terry) use overheads with polarization filters, spinning on tiny motors, attached to the projection head. The resulting effect was richly alive, yet probably cost no more than a few bucks. And it sure got my creative juices flowing.
Lastly, while not intended to do so, overhead projectors are easily altered for smooth fade ins/outs and variable image intensity. Temporarily (or permanently) rewiring the projector to connect it to the lighting system, or for fitting a standard hardware store dimmer in-line between the motor and lamp, is usually an easy operation since there's always a lot of air-space under the hood. Getting your hands in there to work on things really isn't a problem.
So, do I think you ought to throw out your LCD projectors? Should we not lament the eventual passing of the Kodak carousel? No and no. But I do think that the overhead projector doesn't deserve to be ignored as much as it is and that there are things it will do better than anything else. Add one to your bag of tricks. That's always the best solution.
John D. Ervin is the technical director for the Colby College of Theatre & Dance in Maine. Email: firstname.lastname@example.org.