How to Shoot an In-Camera Special Effect: the Matte

Okay, we're not talking state-of-the-art CGI, here, but sometimes you just want to take your student film up a notch. Here's a down and dirty way to add that alien ship or fancy castle to the background of your low budget masterpiece, without the budget busting use of an optical printer.

The basics of the in-camera matte are as follows. First you'll cover up half of the lens and shoot footage only with the open half of the frame--thereby exposing only half of the film. Then, changing the matte to cover the opposite half of the lens, you'll re-run the same footage through the camera, thereby exposing the remaining half of the film, while protecting the footage you've already shot.

Preparation is absolutely critical for this trick to work, but when it does, it can prove to be fairly impressive. For this article, we'll shoot a crowd of bystanders looking up at a UFO hovering overhead. This will use a straight-line matte, which is the least risky, though once you get the hang of it, you can learn to make trickier matte lines.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• 16mm camera matte box (or 8mm, depending on your camera)
• 16mm camera with reversible motor
• Medium to wide angle fixed lens
• Sheet of clear acetate
• Black sharpie
• Black card stock
• Utility knife or scissors
• Black electrical tape
• Patience
• Keen eye for detail

1. The first thing you'll need to do is draw out exactly how you want your shot to look. Lay out a storyboard or sketch of where the crowd will be, and where the UFO will be. Draw a line between them, which is your matte line. Anything below the line will be shot live action, anything above the line will be shot as a miniature later.

2. Scout your location carefully. Remember that anything above your imaginary matte line will be lost when you shoot your UFO, so trees, telephone poles, or anything else that will suddenly disappear halfway up the screen is a no-no. Find yourself a nice simple location with a lot of open sky. It helps if you can set up the miniature portion of your shoot very near the live action portion of the shoot, as you'll want move the camera as minimally as possible--without removing the matte box, or even bumping it too hard.

3. Once you've found your location, set up your camera and attach the matte box to the lens. Tape the acetate over the end of the matte box and carefully trace the outside corners of the matte box onto the acetate with the sharpie. Next, draw your matte line across the center of the acetate.

4. Frame your shot with the acetate--and black line--still on the matte box. The black line will give you a reference for where your matte line will fall when you shoot. Be sure to frame the crowd, including any pointing arms or tall objects, below your matte line or they will be lost when you shoot your UFO footage. Lock off your camera and remove the acetate.

5. Use the matte box edge that you have traced onto the acetate as a guide, and cut the black card stock to fit the end of the matte box, as though you will cover it completely. Then go back and cut your black card into two pieces, using the matte line you've drawn on the acetate.

6. Take the top piece of black card and tape it so that it covers the top half of the shot, leaving only the bottom of the frame exposed.

7. Starting at the beginning of the roll of film (for simplicity), shoot your crowd scene. It is important to make sure there are no lights pointed back at the camera, or bright spots that might flare or create a light blur along the edge of the matte. Also, use a medium to wide fixed lens (not a zoom) at a length that does not put the matte line out of focus. Take careful notes on the starting and ending footage numbers of each good take.

8. In a dark room if possible--otherwise, with the lens completely covered--rewind your film inside the camera to the starting position, re-threading it if you need to. If you do not have a reversible motor on your camera, you'll have to manually rewind the film by hand in a pitch black room or changing bag. Using a 100 foot daylight spool can make this part a lot easier if you don't have a motor. While still in the dark room, advance the camera to the starting footage of the take you want the UFO to appear on.

9. BEFORE you remove the top half of the black card from your matte box, attach the bottom half of the black card to the matte box, taking extra care to align it exactly with the top half of the card. When you have taped the bottom matte to the matte box, it should completely black out the matte box with no overlapping. Once you have secured the bottom matte, CAREFULLY remove the top matte, taking care not to move the bottom matte.

10. Set up your miniature (UFO) sequence for the top half of the frame, and shoot it, re-running the same footage through the camera, but now exposing only the top half of the film. Remember that the same rules apply--anything hanging below the matte line will disappear under the matte and will not appear on the final film.

11. Develop your film as usual.

Tips & Warnings

• Once you get the hang of this, you can begin tracing trickier matte lines onto a glass filter and blacking them out on set.
• Try diagonal or vertical mattes for two people on either end of the phone.
• You can even lock down the camera and re-shoot the same room, having your actor face himself from opposite sides of the screen.
• Precision is key: improper preparation or execution, like misaligning the top and bottom mattes by even a few millimeters, will ruin footage you've already spent half a day shooting.
• Remember, anything static or moving that crosses that matte line will be lost under the matte. Each section of the screen must be treated as though there were an imaginary wall at the matte line.