When using ninhydrin to develop latent prints, which filter should be used for photography?

Using ninhydrin to develop latent prints is a common method in forensic science because it reacts with amino acids in the sweat and oils left behind by fingerprints, producing a purple-blue color. This color change allows for the visualization of prints that might otherwise be invisible.

When photographing developed latent prints, it is important to use the right filter to enhance the visibility of the prints against the background and to capture the true coloration of the ninhydrin reaction. A green filter is particularly effective in this case. The reason for using a green filter is that it helps to block out any additional wavelengths of light that might interfere with the clarity of the print images.

Additionally, the purple-blue color produced by the ninhydrin is complementary to green light. This means that the green filter can help to enhance the contrast between the developed print and the surface on which it has been developed, allowing for a clearer and more defined capture of the fingerprint details. This filtering process ultimately aids in better analyzing and comparing prints for forensic examination.

In summary, a green filter is the most appropriate choice for photographing ninhydrin developed latent prints due to its ability to enhance the contrast and clarity of the images.