Fiat Lux!

July 10, 2006 3:04 PM

Looking for a crash course in "lighting" as it applies to photography.

I'm not interested in photography per se, but the fundamentals of "lighting" (placement, intensity, use of colored lights, indirect lighting, use of reflectors, etc.). These are emulated in several of the 3D rendering programs I use and it's about time to progress from simple McCandless theory or just slapping a bright spot in a render and hoping for the best.

posted by RavinDave to computers & internet (10 comments total)

Almost half of a photography course I did was spent on lighting, and that was scratching the surface. You're combining science (temperature, bulb type etc) with aesthetics (this triangle at the nose looks good on a woman), and that's not really crashable.

I'd recommend a studio portrature course at your local college if you can: you get vastly more understanding just by shifting a spot across the room than you do from reading chapters of a text.
posted by bonaldi at 3:52 PM on July 10, 2006

Yeah, I know full well that people make careers out of this and number many virtuousos among their rank. I don't mean to diminish their craft by implying that I can master it from a few wiki pages of info ... but I really do need a broad generalized outline if only so I can properly articulate the finer points I'll need to study more in depth.
posted by RavinDave at 4:04 PM on July 10, 2006

I second everything Bonaldi just said. However, if you're looking for a book that'll get you started, check out Matters of Light and Depth by.. I'm fairly sure its Ross (?) Lowell (as in, the guy who owns the company that makes many mid-grade portable lights). It has a pretty thorough introduction to lighting for photography and video. I'd also recomend Cinematography by Blaine Brown, which, while not nearly as good as the Lowell book, also has chapters on framing and motion composition, which may come in handy if you're looking to get started in animation as well as rendering. Get that one at a library if you can.

You might want to look into some texts on the physics of light and the relation between your shader toolset and the real world. There are numerous tutorials out there online, if you google. Even the ones not specific to your package of choice may be helpful in terms of describing concepts.
posted by Alterscape at 4:08 PM on July 10, 2006

Light: Science and Magic is the first, and sometimes only book on light I ever recommend. It really helps you understand the principles so you can apply them with whatever's in your toolkit.

There are a few "big" concepts that will help you get started. The first is that the larger your light source, the softer the shadows. The sun, while physically quite large, in lighting terms is basically a point of light. That's why shadows are so harsh in direct sunlight. When it's overcast, the clouds scatter the light and create a giant soft-box effect. This is why photos taken of people in front of walls with simple flashes have nasty shadows, while pictures taken with a bounced flash (or a diffuser) have softer shadows. The bigger the apparent light souce, the softer the shadows. Remember that one.

Another "biggy" concept: the Inverse Square Law. The ISL states that for any change in distance of the light from your subject, the amount of light output to equal the original exposure is the square of the distance. In other words, if your flash can give you a proper exposure with 1/4 power at 10 feet away, you'll need full power if you move 20 feet away. The ISL is great for making mince-meat out of onboard camera flashes. You know when you go to a sporting event and you see those idiots taking pictures with a flash when their subject is 100 feet away? The amount of light needed to properly illuminate the subject is so ridiculously more than their little flash could ever provide... all they do is illuminate the foreground.

The ISL also dictates how light will fall off over distance. So if you're taking a picture of a group of people 5 ft. away, and their friends are 10 ft. away, they're only going to get a quarter of the light that the foreground people are getting. Expose for the foreground folks, and the background folks turn to black. Expose for the background folks, and your foreground folks look like they're staring into a supernova.

What else... what else...

Oh yeah, this is a hard one for photographers to first wrap their heads around when they've been playing with f-stops and apertures all their lives: for the most part, the flash freezes the action, not the shutter. Ever see those pictures of a hummingbird with its wings frozen in mid-flight? You'd need a crazy-sick shutter speed to capture that kind of speed. And, as you know, increase the shutter speed to crazy-sick proportions, and all of a sudden you aren't getting any light. What to do, what to do?

The answer: your flash! Set the shutter speed to whatever you like. 1/250th of a second, 1/15th of a second... shit, how about 5 seconds? Doesn't matter. The flash is freezing your subject, not your shutter. The shorter the duration of the flash, the less motion you expose. You can adjust the "speed" of your flash by decreasing the power output. Some flashes let you go down to 1/16th power or less, effectively allowing you to capture action at ten thousandths of a second. Of course, reduce the flash output, reduce the light. So if you want to play Doc Edgerton and shoot bullets into balloons, you're going to need a really, really powerful flash to start out with.

Agh. There's so much more. Anyway, that's a start... give that book a read and don't be afraid to ask questions.
posted by Civil_Disobedient at 4:29 PM on July 10, 2006 [2 favorites]

Just to quickly add a little tip off the last point:

Ever notice whenever you see a professional picture taken at nighttime, the people are always so nicely exposed, and yet you can also see all the city lights and such? But when you try and take a picture of your friends at night, you don't see any of the atmosphere. No neon, no spice... just your friends illuminated like deer in headlights.

The reason why relates to the last point I mentioned. When you illuminate your friends with a flash, all of a sudden the background can't compete. If you set your camera to moron, it says, "Hey, a flash! Great, now I can shoot at 1/125th of a second!" And so it does, and your friends come out nicely exposed, but the atmosphere falls into black.

The problem can better be illustrated if you remove the flash and your friends from "the picture." What kind of exposure would you need to take a photo of a city street at night? A really long-ass exposure, that's what. Maybe 1/15th of a second at f/2.8. That's what the background needs to expose properly.

Now bring back your friends. OK, so the city "needs" 1/15th of a second to expose properly. But your friends, well, they're not so happy about the idea of standing completely motionless for 1/15th of a second. Goddamned breathers. So what do you do?

Now here's the trick: drag the shutter. What that means is, set your flash to expose properly for a compromise speed... say, 1/60th of a second. Then, set your camera to instead expose for the proper 1/15th of a second that the background needs. What will happen is that the flash will "freeze" your subjects long enough to get them crisp and in focus, but because the shutter is left open slightly longer, the light from the city can bleed into the shot and properly expose. The only side effect is that you might have a very slight "ghost" halo around your sharply-exposed friends (if they're moving around). But this is a small, small price to pay for a really good night-scene shot with flash and friends.
posted by Civil_Disobedient at 4:44 PM on July 10, 2006 [1 favorite]

Flash is interesting but probably not really relevant to 3D modeling, where you can have as much "light" as you need by changing a number. You might actually look into lighting as practiced by videographers etc. as it will probably have more in common with 3D stuff.
posted by kindall at 8:31 PM on July 10, 2006

This is all great stuff and I thank you mightily -- the schooling provided by Prof. Civil_Disobedient. After doing some scouting, I'm particularly wondering about rules of thumb and axioms about using colored lights; any caveats or insights.
posted by RavinDave at 9:23 PM on July 10, 2006

RD: I could give you a dozen and it wouldn't begin to scratch the surface. So instead, I'm going to give you some homework.

Read this link, every single page of it. This is the website of Neil Turner, a freelance portrait photog in Great Britain. Each one of those links on that page are a case-study. What I like most about Neil's writing is that he explains real-life solutions to situations and problems that arose (running out of time, bad light, subject was fidgety, etc.) while trying to capture a specific mood.

Experience is the best teacher you can ever have. Someone else's experience is the second-best.
posted by Civil_Disobedient at 1:00 AM on July 11, 2006 [1 favorite]

Arg, he used to be freelance. Now he works for the Times.
posted by Civil_Disobedient at 1:02 AM on July 11, 2006

Civil_Disobedient writes "If you set your camera to moron, "

I love that phrase, it's so true. Even the 3D Colour matrix meter in my D70 isn't smart enough to drag the shutter.
posted by Mitheral at 9:25 AM on July 11, 2006