Forensic Photography: A Practitioner's Guide

5 Light as a Forensic Photographer's Tool

5.1 Overview of alternative light sources (ALS)

Photography in general, and forensic photography in particular, requires the understanding, control and use of light. Some types of light, such as electronic flash, may be used as a general illumination, whilst others, such as a laser, may have a more specialist role to play in revealing latent evidence. In this chapter I want to look at using these artificial types of light, or ‘Alternative Light Sources’, as forensic tools.

I am not going cover the actual photographic technique directly here, as this will be covered as we apply the illumination in different ways in subsequent chapters. I hope this chapter will provide bedrock of understanding for the range and diversity of lighting choices we actually have.

Although many forces own ALS, in my experience they often have little experience of using these types of lighting beyond the confines of the laboratory. This is a shame, as I believe they are at their most effective and cost efficient when deployed to crime scenes. For my part, I have spent the last 20+ years using and researching ALS to collect latent evidence, and am still amazed at what can be found.

So exactly what is an ALS? Most forensic books or guides take a traditional view on this. To many people, ALS are devices that produce filtered or coloured light in one form or another, such as a Crimescope or laser (see below). I believe, however, that the definition should be much ...