Reverse Engineering Other Shooters' Light
You cannot hide how you lit something. Everything about the light - style, color, direction, size, beam spread, etc., - is on display for any shooter with something between his or her ears to figure out.
You should be able to deconstruct the light used by others.
Here are some starters.
Q: Where did the light come from?
A: The shadows will tell you.
Q: Were there multiple sources?
A: If the light appears to be coming from multiple directions (assuming no mirrors) probably. Also check for inconsistent shadows.
Q: Was the strobe light balanced?
A: Well, do the florescents look, say, white? There you go. Ditto tungsten, etc.
Q: Is the light falling over a small, restricted area?
A: Snoot or grid.
Q: What is the easiest way to check the style of the front light in a portrait?
A: Eyes make good mirrors to see the light sources. If they are wearing sunglasses, you are golden. Unless they Photoshopped it. And no, you cannot do that if you are a journalist. And if you are a Strobist, you shouldn't have to.
Q: Was the light nearby?
A: Check how fast it falls off as it travels across the subject. Fast? Yes. Slow or none? No.
Q: Was the light source large?
A: Depends on how close it is. A small, shoe-mount flash head looks like a softbox from 2" away on a macro shot. The sun, which is the largest light source you'll likely be using, is pretty hard because of the 93,000,000 mile thing. It is all about how big the light appears to the subject.
Q: Is that light strobe or continuous?
A: That can be a toughie. You can use available light effectively enough to fool people.
Q: How did they get that overcast sky so neon blue?
A: Set the camera balance to tungsten, which renders the formerly neutral clouds blue. Underexpose the sky (to, say, a stop below medium grey) for more of an effect. Then, CTO-gel the flash lighting your subject to render the light hitting it as white and you have the effect.
Q: This is starting to sound random and incoherent. Are you OK?
A: Yes, it is. And no, I am not. I am home sick from work today, feeling like I got runover by a train. I will add more to it later when I am more lucid.
But I hope you are starting to get the idea that there are no secrets when it comes to light.
Next: Know Your Flash