Masks

Block portions of a scene & make double exposures

Note: This technique only works with a traditional film camera. Digital cameras cannot be used for multiple exposures, although they can be used to make two masked images that can be digitally "stitched" together using image-editing software.

Masks are devices that block light from a portion of the scene. They are not filters, although many filter makers term them as such. A lens cap with a hole drilled through it would qualify as a mask since only the light passing through the hole would reach the film while the rest is masked.

If the hole was in a particular shape – a circle for example – a subject could be photographed through the hole and the resulting image would have the subject framed as a circular vignette.

Masks are typically available as squares or rectangles that fit into the slots of a filter system.

PRE-SHAPED MASKS

Opaque black masks with cut-out centers in the shape of binoculars, keyholes, hearts, circles, ovals and other shapes are available from many filter manufacturers. Maximum depth of field and long focal length lenses produce the best results, which are further improved if the subject is well lit and the background is bright.

DOUBLE MASK SETS

Double masks involve two squares (or rectangles), one of which is mainly opaque while the other is mainly transparent. The cut-out shape in the opaque material is replicated as a solid shape on the clear material, sort of like positive and negative images of the same subject. They are used for double-exposures where one exposure is made with one mask in place in front of the lens and the second exposure on the same film frame is made with the other complementary mask in place. This causes one image to be surrounded by another image in the same picture, with slight blurring at the border zone. Double masks are available in two versions, one for short focal lengths (21 mm to 35 mm lenses) and one for longer focal lengths (50 mm to 105 mm).

MAKE YOUR OWN MASKS AND MASK SETS

Blank mask sets can be purchased where some of the squares or rectangles are totally opaque and others are totally clear and colorless, allowing the photographer to cut and paste the masks in whatever shapes he or she desires, without having to center the cut-outs. The shape that was cut out of the black material must be precisely affixed to the clear material in the same manner as a double mask.

USING DOUBLE MASK SETS

In order to use the masks:
(1) auto-focus must be shot off.
(2) Exposure readings are taken without a mask in place.
(3) For short focal lengths (21 mm to 35 mm lenses), aperture settings between ƒ5.6 and ƒ8 are recommended.
(4) For longer focal lengths (50 mm to 105 mm lenses), apertures between ƒ11 and ƒ16 must be selected.
(5) The mask must be carefully-centered in the filter holder, in the filter slot that is neither the closest nor the farthest from the lens – usually the second one from the lens.
(6) With the first mask in place, an exposure is made, and the shutter is cocked without winding the film forward. (This is usually achieved by depressing the film rewind button while advancing the film-advance lever.)
(7) The first mask is removed and the second mask is placed in the same slot for the second exposure.
(8) Be sure to advance the film and make an exposure of total darkness (i.e. with the lens cap on) just in case the film did not fully advance.
(9) Advance the film one more time, and you are ready to expose the next frame.

DOUBLE EXPOSURE MASK

A single mask that has one-half clear and one half opaque permits double-exposures in which you can have the same person or object appear twice in one image. The person will seem to have been photographed with an identical twin.

The theory is simple: one half of the scene is blocked off during the first exposure; the filter is rotated to block off the other half for the second exposure. The subject is photographed through the clear half of the mask, and without moving the camera at all, the subject is repositioned to be visible through the clear portion of the rotated mask for the second exposure.

The procedure for making a double-exposure is identical to the manner in which you use a double mask set (see above), except you rotate rather than replace the mask for the second exposure. You must also take steps to ensure the overall picture is sharp and believable.

HINTS FOR A CREDIBLE DOUBLE EXPOSURE

(1) The subject must be totally within the half of the scene that is not blocked by the mask. This is difficult to judge when looking through the viewfinder since you can see usually see more of the overall scene than the film will record.
(2) Don’t allow your subject’s legs or arms to approach the middle zone, or they may partially disappear in the final image, as shown in the picture above.
(3) There should be a solid, immobile object (a table, car or counter top, for example) in the middle of the scene that will be photographed half in one exposure and half in the other, creating an entire image of it in the finished product. Take care that your subject does not move this object when he or she is switching from one side of the scene to the other, not even a millimeter.

(4) A solid tripod is essential to ensure the camera remains in precisely the same position for both exposures.
(5) Some cameras have their film rewind button on the bottom of the baseplate. If your camera does, be sure you attach the camera to the tripod in a manner that allows you access to its film rewind button without having to remove the camera from the tripod. This way, you can depress the rewind button to prevent the film from advancing when cocking the shutter for the second exposure.
(6) Have your subject change into a second outfit for the second exposure, and it will add to the illusion of identical twins.
(7) If you have an assistant available, position your assistant on the dark side so your subject can look at him or her, then for the second exposure, your subject should assume the same position and posture that the assistant was in. In the final picture, it will seem that your subject is looking directly at him or herself.