One caveat before we get started on this topic. I am not a fan of giving everything photographers do a name. It does make it easier to talk about, but it’s not like your customer is going to come to you saying, I really love how well you do loop lighting. And just because you use some technique that has a name, doesn’t mean that it’s going to be good.
The best way to talk about this would be hours on a clock, with the camera at 6 pointed at 12.
Backlight or Rim Lighting
This is when the light is behind your subject at 12 o’clock and it can result in nice rim lighting. If you have the subject standing in profile, have them turn their head just right, you can end up with a catch light.
This is when you boom a light at 6 o’clock slightly above and in front of your model so that it places highlights on their cheeks and a shadow under their nose that resembles a butterfly, allegedly, but I don’t see it. I guess I failed this Rorschach test. It will also exentuate their deep set eyes, but if you place it just right you can get light on their upper eye lids, which I always prefer.
Clamshell lighting is when you do butterfly lighting or add a reflector or a softbox under the other light for fill. Just imagine seeing this from the side, and you will see the shape of an open clamshell.
Is when the light is closer to 4 or 8 and far enough away that the shadow from the subject’s nose might extend to the shadow from their cheek. It will also create an upside-down triangle-shaped light under their eye opposite the main light. This is not possible with all faces, but it is named after the Dutch painter who likely posed people near a window. This type of lighting is one of my faves and I will often end up using this lighting or loop.
Broad lighting is similar to short lighting but you have them step back a little and turn them away from the light. In this position they should have light on both eyes but the lit part of their face will appear broader.