Transfering artwork to digital domain sm
  • Overview
  • Transcript

3.1 Positioning Lights

In this lesson you will learn how to take advantage of the inverse square law to get very even lighting and keep the reflections out of the camera!

Related Links

3.1 Positioning Lights

In this lesson, you're gonna learn how to position the lights, how to take advantage of the inverse-square law, and how to keep reflections out of the camera. First, let me go over the lighting rig that I'm going to use. Now, when it comes to lighting up these photos, there are a lot of options. You can use studio strobes, you can use speed lights, you can use a constant lighting source, LED, tungsten Halogen, fluorescent. I'm going to use compact fluorescent lamps that have a high CRI. I like these over the other options because they don't change over a period of time in terms of their output or their color temperature. These are things that can sometimes happen with studio strobes and speed lights. Speed lights have batteries, so over time as your batteries die they can potentially give you a lower output and that can mess with your exposure. In some studio strobes can alter their color temperature between exposures to some degree. With these CFLs, they're pretty constant and pretty stable over long periods of time. Now, I like these particular CFLs because they have a pretty good CRI. CRI is a measurement of how well a lighting source does at reproducing a specific group of colors. So a specific red, a blue, a green, so on and so forth. Now, the CRI standard or measurement does not cover every color, but it's something that you can use to get an idea of how well the light will perform in terms of color reproduction. And when it comes to photography, color reproduction is important. Now, the sun is the gold standard of color that has perfect color and it has a CLI of 100, that's basically as good as it gets. These particular lights that I'm going to use have a CRI of 93, which is pretty good. There are some better compact flourescent lamps out there that have a CRI of 95 or 96, but that much difference in CRI is not really that noticeable. Your typical household standard LED lights or CFLs have a CRI of around 80 or 85, somewhere in that range. That is not really good enough for photography purposes. That's fine for lighting up your house and I'm sure it looks good to your eye, but cameras don't see colors the way your eyes see colors. So you wanna shoot for a high CRI lamp. Now, what I'm going to be using are these blue max HD lighting lamps. I found these online, they're about $10 a piece, specifically they are the 26 watt versions. So they're not incredibly bright, but they do have a CRI of 93 and that's about the best that I've found in terms of price to color performance. So I'm using one of these in each one of these light modifiers and all these are an umbrella softbox or octobox. So this device here basically opens up like a standard protect-you-from-the-rain umbrella, but it has a slightly different shape to it and it's also no good in the rain. The inside is lined with a silver shiny reflective material. In the front, has this nice white translucent diffusion panel that makes a very even and a very broad lighting source. To hold the CFL, there is a socket stand adaptor. It's basically just a little socket that you can screw in your lightbulb and it has an umbrella shaft holder, and it also attaches to a photography or a video style light stand. And I'm using two light stands. I'm basically using two identical set ups here because I want even light to come from both sides and these are large enough that it will basically cover and give me a nice, even exposure over this whole area here. The nice thing about this is compared to speed lights or studio strobes, this is very inexpensive. It's probably less than $150 to $200, depending on what kind of parts you already have and where you find the stuff here. Even a $200 is going to be less than probably one studio strobe or speedlight. So this is a great set up, it all collapses down very small and it works very well. So let's talk about how to position these lights so that we can get a nice, even field of light down here and keep the lights out of the reflection of the camera. Now, this is gonna be pretty easy to do because there's something called the inverse-square law. Now, we don't have to get super into how the inverse square law works, but basically, let's take a look at just what one of these lights is going to do. So right now I've killed all the other lights in the studio, and I'm only lighting up this space with just this one light here so you can see. Now, the inverse-square law states that for every doubling of the distance away from the lighting source, the light will fall off, basically 75%. The light is one quarter as bright. So if I were to take the measurement here, whatever it is, three feet, and if I move this six feet away, now the light will be only 25% as bright here. So what that means is that the closer I move the light to the subject, the faster the light gets darker. So you can see right here if I just hold this focus target up and I position it relatively flat, I can probably cheat this by tipping this. But if I put this on the same plane as my little thing here, you can see that there's a bright spot here and it's getting darker. But if I move this over, you can see that the exposure becomes much more even. So what I probably wanna do is take these lights and move them a good distance away, but I don't want them so far away that I'm not getting a proper amount of light here to make a good exposure. I don't wanna have a 25 second exposure, that's not really gonna work so great. That's gonna kinda slow down my process here. The other thing I wanna keep in mind is that I don't want reflections from the light to interfere with my photos. Now, you maybe you're wondering why the light's positioned like this, or tilted like this, rather than kind of from above, like this. And that's because of reflections. Now, this is really easy to figure out. Basically, you can set something slightly reflective down on your rig and then take a flashlight and look in your camera and hold the flashlight, and you will see exactly where you are starting to get a reflection. And that's going to let you know that's right where the family of angles for the subject that you're shooting starts. So basically, for this rig right here, That's right about here. So if I got this light closer, right about here, I would start to get just a little bit of reflection right here on this edge because of the angle that I'm shooting here and where the camera is positioned. So I wanna make sure that I'm keeping things out of these kind of family of angles here, so that I'm not getting a direct reflection from my lighting source. That's also why I killed all the other lights in this space because if I had, for example, a light directly above here, I would most definitely see that reflection in these photos and that would not be good. Now, the best way to determine your lights position and how that's affecting your exposure and how to set your shutter speed once you have your other settings dialed in, is to use a light meter. And that's coming up next.

Back to the top