Keep ’em cool. Video projectors need air flow. Even super-efficient LED projectors need fans and fresh air to keep from overheating, which can drastically shorten the life of your projector. Keep air flow in mind when figuring out where to hide the projectors in your haunt. Do not block the vents.
Keep ’em dry. Moisture is another enemy of projectors (as with most electronics). I run my projectors outside at night. They’re protected from direct rain, but you also have to contend with dew. While they’re running, they keep warm enough to fend off condensation. But at the end of the night, bring them inside, along with any electronic devices you use for playback.
Thumb screws. Smaller projectors often have a single screw hole in the bottom for mounting. This is a tripod mount. You want a 1/4”-20 screw. (The 1/4” refers to the diameter of the screw, and the 20 means 20 turns of the threading per inch. We’re talking machine screws. I know you’re all haunters, but not everything takes kindly to drywall screws.) Don’t turn the screw too far. The tripod mounting hole is only 1/4” deep. Hardware stores often have little baggies of 1-inch long 1/4”-20 “thumb screws” that are perfect for temporarily attaching a projector to some 3/4” plywood that’s part of your set. Drill a 5/16” diameter hole through the wood, slide the screw into it, and twist it into the projector on the other side. If the projector jiggles once you screw it in, add a washer as a spacer. (Remember to ensure proper air flow.)
Screw ’em all. Larger projectors often have four screw holes for mounting. I believe these are usually 1/4”-20, just like the tripod mounts, so the thumbscrews-through-plywood trick might work. But projector mounts aren’t as standardized as tripod mounts. If you salvage a flat-screen television mount, it might fit your projector.
Scotty, we need more power! If your little LED projector uses USB for power, be aware that many of the cheaper USB power adaptors and their cables may not provide enough current (Amps). If the projector has a battery pack, it may seem to work only to run out of juice an hour into your haunt because the projector drains the battery faster than the USB recharges it. Good power adaptors should be marked to say how many amps they deliver. Look for at least 1 Amp. Do a test run before the haunt, and mark the good power adaptors with a label for faster setup.
Did you hear something? Built-in speakers on projectors are generally terrible and exist primarily so marketing folks can advertise “built-in speaker” on the packaging. The good news is that most projectors have a 3.5mm audio out jack that you can connect to better speakers. The even better news is that decent speakers can be dirt cheap. I use the absolute cheapest “powered PC speakers” I can find. I literally bought a pair at Fry’s for less than $10 (including sales tax). I’ve used them for years, and they sound fine. Many of them are black, so they’re easy to hide, too. The only real drawback is that it’s one more thing to plug in.
It’s pretty dark out here. The farther the projector is from the screen, the larger the image will be, which is great, but it’ll also be dimmer. Much dimmer. The brightness drops dramatically with the “throw” distance. In a dark haunt environment, that may not be an issue, but keep it in mind when planning.
As gray as a ghoul in a graveyard. Video projectors aren’t really good at black. The bits that are supposed to be black will be gray. With a high-priced projector, it might be a really dark gray, but it’ll still be gray. Generally speaking DLP projectors will give darker “blacks” than CMOS or LCD.
An aura of foreboding. Because projector black isn’t truly black, watch out for the tell-tale rectangle of light that your victims might see around the projected effect. It’s a real give-away that this is a technical effect rather than a supernatural one. You can often adjust your set, props, and lighting to hide or eliminate it. A talking jack o’lantern in front of a wall will look bad. If you can move the pumpkin away from the wall and then wash the wall with other lights, you can effectively hide the tell-tale frame. My tombstone projection was carefully designed to exactly fit the projector frame. The little bit that spills over the “shoulders” of the tombstone hits nothing that reflects back.
A bargain with the devil. Consumer home-theatre projectors sometimes have an “economy” setting that lowers the brightness of the bulb. This not only greatly extends the life of the (often very expensive) lamp, but it might also be a more appropriate light level for a haunt. Win-win!
Zoom! Some people confuse zoom lenses with telephoto lenses. A telephoto lens (often called a “long throw” lens) gives a smaller image than a regular lens at the same distance. A zoom lens lets you change the size of the image without moving the projector. Zoom lenses generally add to the cost. If your effect demands precise alignment, a zoom lens might help. If you need to put the projector far away from the screen, you can use a zoom lens like a telephoto lens.
Don’t shoot straight. Most projectors project the center of the image higher than the projector itself. This can be useful in hiding the projector (if you plan for it). There are “very short throw” projectors for home theaters where this is a huge factor. It seems to be less of a factor in smaller projectors, but even many of the tiny ones have an “up” bias.
Spirits on another plane. You can front-project on almost anything: walls, fences, tombstones, etc. The less it looks like a flat vertical screen, the better the illusion: pumpkins, statues, the ground. There are limits of how three-dimensional the screen can be if you need the entire image to be in sharp focus (unless you have a laser projector). But for abstract images and translucent apparitions, experiment with fog, water, billowing cheesecloth, and window screen material.
Sneaking up from behind. Rear screen projection can be a cool solution to hiding the projector from your victims. You can rear project onto various fabrics (including theatrical skrim, but bedsheets work, too), frosted windows, plastic shower curtains, paper, etc. You’ll have to experiment to see what works best for the effect you want. If you want to project on a bit of plastic or glass that’s too clear, paint it with repeated coats of a matte finish spray. The instructions will tell you to not use too many coats to avoid making the object dull, but that’s exactly what you want. I’ve had good results with Krylon Matte Finish.
Don’t look directly at the gorgon nor into the eyes of Mara. Watch out for “hot spots” when using rear-projection. You want to avoid placing things such that the viewing angle would be directly at the center of the lens. Those spots will appear washed out and ruin the illusion. Find a way to offset the projector, which may mean altering your media to accommodate projecting from off-center. Remember that most projectors bias the direct line-of-sight up. That can help or hurt you.
Looping into eternity. The simplest projection effects run in a loop, cycling frequently enough that most guests will see it but not so frequently that they’ll see it twice. So your video might be anywhere from 30 seconds to 5 minutes long. Most DVD players and digital media players can be set to show the same video over and over. The problem is that, even if your video is perfectly seamless, many players will actually go blank for a second or two whenever the video restarts. The worst ones will flash a menu up. To minimize this problem, use video editing software to make a long video consisting of your short clip run over and over again. Consider using a fade in at the beginning of the first copy of the clip and a fade out at the end of the last.
Listen to them, the children of the night. What music they make! A lot of video effects don’t require sound effects: A jack o’lantern that occasionally looks around needn’t speak. Consider taking advantage of that unused audio track by adding ambient sound effects or music that fit the scene. You can pipe it to speakers placed elsewhere, so that nobody associates it with the video effect.
Lurking in the shadows. One way to think about a projector is as a light source with custom shadows. Try putting one where an actual light source is (or could be) and project some surprising shadows. The best bang-for-the-buck effect I’ve ever made was to point a video camera at a blank wall while I staggered around like a zombie casting a shadow on the wall. I looped the video so that the shadow appeared once every few minutes. I set up a projector on a tripod in the backyard and pointed it a frosted window. From inside the house, when there was no shadow, it looked like moonlight or a streetlight was hitting the window. But when the shadow lumbered into view, several party guests were utterly terrified. One was convinced we’d hired an actor to stalk around the backyard all night. I had spent less than 45 minutes on the effect, and it was easily the hit of the party. People were imagining a fully made up and costumed actor when it was just a 30 second video of a shadow. Imagination is powerful. Exploit it!
Ethereally abstract. A lot of the commercial video content (like that from AtmosFEAR) is very literal: well-defined ghosts, skeletons, bugs, witches. It’s stuff that’s designed to be projected on flat surfaces. There’s nothing wrong with that, but I encourage you to experiment with more abstract images: vague ghost shapes on diaphanous material suggest the presence of spirits to a vivid imagination, a flickering spot of yellow on a tombstone can convince you the marker is actually illuminated by the candles in front of it, a couple circles of color swirling around become dancing shafts of spectral energy when projected through fog.
Spooky landscapes and portraits. The aspect ratio of a projector is the width of the image divided by the height. Typical projector aspect ratios are 4:3 or 16:9, that is, they’re wider than they are tall. This is called “landscape mode.” Remember that you could design your video to be projected sideways, in “portrait mode,” so that the longer dimension is the height instead of the width. This might be the best choice for a tall, narrow tombstone, as it takes best advantage of the projector’s resolution. For a small projector, you can quickly connect two scraps of plywood into an L-shape and use a thumbscrew to attach the projector (using its tripod mount) sideways to the vertical piece. Remember that the “up-bias” of the projector will become a left- or right-bias if you turn the projector.