Use an optical prism for vintage effects

Throw the rulebook out of the window and inject your shots with an eye-catching element of chance by shooting through an optical prism. With this piece of glass held in front of the lens, two images will never be the same. But what you will get is a ghostly reflection around you, mixed with colourful dispersed light. 

So how does it work? When white light is dispersed you can see its constituent colours. These are violet, blue, green, yellow, orange and red. If you’ve seen Pink Floyd’s famous album cover for Dark Side of the Moon, you’ve seen what happens when light is dispersed through a prism.

Holding a prism on the right side of the lens has made light disperse from the top-right corner of the frame so it could be balanced in the composition.

Holding a prism on the right side of the lens has made light disperse from the top-right corner of the frame so it could be balanced in the composition.

How to shoot it

Shooting with a prism is an easy technique you can try with any camera and lens. You generally shoot and focus how you would normally, but the main difference is that you hold the prism at the edge of the lens and move it around until you can see the effect.

Trial and error is key for this technique, and it can take a few minutes of experimenting to find what works best. We found shooting in landscape format was easiest because we could hold the camera normally, and then hold the prism close to the bottom of the lens. Portrait format was slightly more difficult because the prism still worked bestat the bottom of the lens. This meant holding the camera upright with the left hand (see the behind-the-scenes image here), which the camera isn’t designed for. The prism is then held with the right hand. It feels strange, but once you’ve got a firm grip of the camera and a finger on the shutter button you’re ready to start shooting.

One thing to be mindful of is that autofocus can struggle with light being scattered into the lens by the prism. If this happens move the prism away from the lens, focus and keep the shutter button depressed halfway, and then move it back into position ready to shoot.

The prism doesn’t need to be held directly in front of the lens. Holding it at the edge disperses light into the lens perfectly, which can be seen in the viewfinder.

The prism doesn’t need to be held directly in front of the lens. Holding it at the edge disperses light into the lens perfectly, which can be seen in the viewfinder.

This article was first published in the September 2014 issue of Practical Photography - download back issues here.