Think Rim Light or Back Lighting

Nikon D750, Sigma 120-300mm ƒ/2.8 DG OS HSM | S, Sigma TC-2001 2x, ISO 12800, ƒ/5.6, 1/200

The back light also called a rim, hair, or shoulder light, shines on the subject from behind, often  to one side or the other. It gives the subject a rim of light, serving to separate the subject from the background and highlighting contours.

Not having this light you can see the difference here in this second photo where the lighting crew forgot to turn on the back light.

Nikon D750, Sigma 120-300mm ƒ/2.8 DG OS HSM | S, ISO 4500, ƒ/2.8, 1/80

In one of my masters classes I took at the Maine Photography Workshop the instructor always started first with their back light to create the separation in all his photos. This was important in where he had mixed lighting.

Nikon D750, Sigma 120-300mm ƒ/2.8 DG OS HSM | S, Sigma TC-2001 2x, ISO 10000, ƒ/5.6, 1/250

While in theater you can really see it because often there is a black background, using a back light really helps create depth into your photos. It helps create those layers from front to back in photographs.

Nikon D750, Sigma 70-200mm f/2.8 EX DG APO OS HSM,  ISO 360, ƒ/2.8, 1/80

In theater and most of photography a 3 – point lighting setup is quite standard.

The backlight can be on the side or directly behind the subject. it is different from a kicker light that catches the sides of the face for example in a photo.

Nikon D750, Sigma 24-105mm f/4 DG OS HSM Art Lens, ISO 100, ƒ/8, 1/60 – 2 Alienbees B1600s for main light

The sun is the backlight in this photo. The Alienbees studio strobes are the main or key light to the right of the camera. The open sky is the fill light.

If you want to create depth, layers and separation of your subjects from the back ground then be sure and use a back light.

My suggestion is that is the first light you think about adding to any scene.