How Does an Opaque Projector Work?

An opaque projector works by shining a bright light onto a nontransparent object. The light is reflected from the object and through a series of mirrors or prisms and a lens. This allows the user to enlarge and transfer an image from a small, opaque source to a larger surface such as a screen or canvas.

Early projectors were called "magic lanterns." The earliest ones shined a light through glass slides with painted images. As printing evolved, manufacturers were able to produce glass slides with images printed on them rather than painted. These projectors worked by transmitting light through a transparent object. This transmitted light is known as "diascopic illumination."

By contrast, an episcope projector could use reflected light to project images. The projector would shine a bright light onto the opaque object. The light would be directed by several mirrors or prisms out to the lens. The projector allowed you to focus the lens to alter the size of the image.

Early episcope projectors were used to view images from postcards, pictures from magazines, advertising cards and even images supplied by the projector’s manufacturer. An episcope or opaque projector could even be used to view small, three-dimensional objects such as coins, leaves or insects.

It wasn’t long before manufacturers combined the ability to view transparent and opaque objects into one device. An epidiascope allowed the user to view both slides and opaque objects.

Educators appreciated the ability to project pages of books, printed material and photographs as well as slides or transparencies so that the entire classroom could view the material together. Modern classrooms are now more likely to have projectors connected to computers. However, epidiascope projectors certainly advanced classroom instruction in their time.

Unlike an overhead or slide projector, an opaque projector does not require you to first transfer your image to something transparent. The opaque projector allows you to work directly from a photograph as long as the photo is small enough to fit on the opaque projector’s stage. This ability has made opaque projectors very popular with photorealistic artists.

The artist can take a photograph of what he would like to draw or paint on a larger surface. As long as the photograph can fit into the opaque projector, the artist can enlarge it on a canvas or other surface to trace and paint. Some artists even use this method to create murals on walls.

For art, opaque projectors are best used when working on a scale of 18 by 24 inches or larger. Smaller works will benefit from other transfer methods. Opaque projectors usually have a stage – the area where you put your opaque object – of about 5 to 7 inches square. If you are transferring from a photograph, make sure it is small enough to fit.

You will place the photograph or object on the projector’s stage. Then, turn on the projector and turn off the lights in the room. Next, adjust the image until it is your desired size, and it is positioned correctly on your work surface. Be sure the image is not warped or distorted due to the projector or the canvas being placed at an odd angle.

Secure the projector so it will not shift once you begin your work. Then, trace the outlines of the image onto your canvas, wall or other work surface. Once you have your outlines, it is safe to turn off your projector and keep working on the details of the image.

Be sure you have enough time to completely transfer the image before you begin. If your projector gets bumped even slightly out of alignment, it can be very frustrating to try to get the image back into the correct position.