|Nikon D750, Sigma 120-300mm ƒ/2.8 DG OS HSM | S, Sigma TC-2001 2x, ISO 12800, ƒ/5.6, 1/200|
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|
|Nikon D750, Sigma 120-300mm ƒ/2.8 DG OS HSM | S, Sigma TC-2001 2x, ISO 10000, ƒ/5.6, 1/250|
|Nikon D750, Sigma 70-200mm f/2.8 EX DG APO OS HSM, ISO 360, ƒ/2.8, 1/80|
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|
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.