By Volker Betz

Ring lights are common devices for close up photography. They a typical mounted around the lens and light direct in direction of the object. This is fine in many cases, but fails mostly with mineral specimens.

Dark field illumination is a lightning method common in microscopy. The light is directed in a almost 90 ° angel to the view of the camera. It is a superb method to photograph coins, as it enhances contrast on flat lustrous objects and is also useful for macro photography of minerals.

Experiments showed that gives good results in many cases. The method can also be transferred to the close up range and larger objects if a ring light of sufficient diameter is used. As a rule of thumb, the diameter must be about twice the largest dimension of the specimen.

A ring light is easy to make by just glueing self adhesive LED stripes ( cold white ~ 6000 K) into a cylindrical plastic container. The cover of the container is not used and the bottom cut off. It can be hight adjusted by means of a small stand from aluminum profile (see picture) and some screws.



Photography is done typical in a vertical setup, with the the specimen mounted a few cm above a glass plate with black background, or a sheet of acryl glass for light background.

The method gives good results also with samples which have very litte contrast, like the shown natrolite specimen.