If you have used a camera for any length of time you're familiar with the idea that your camera has the ability to change something called white balance. Does this mean that white light is not white? Yes it does! In this lesson you will find out why.
1.Introduction1 lesson, 01:54
2.What Is Light?4 lessons, 35:29
3.Light Transfer2 lessons, 09:20
4.Types of Reflection3 lessons, 13:37
5.Conclusion1 lesson, 01:46
If you've been shooting on a camera for any length of time, you'll be very familiar with the idea that your camera has the ability to change something called white balance. Does this mean that white light is not white? Yes, it does. And in this lesson, you will find out why. Let me ask you another question. Do cameras see the same way you and I see? Yes, in a lot of ways they do. A camera system and your eye both have lenses to focus the light, they both have a device to regulate how much light is entering the system. On a camera this is the aperture, and on your eye, this is the iris. They both have a system for gathering and interpreting information about the light that is entering the system. Your camera has a sensor and your eye has the optical nerve. And in terms of color they both work in a similar way. Our eyes have cones that are most sensitive to three types of colors, red, green, and blue, and even though we have more red cones in our eyes, we are most sensitive to green light. Similarly, in almost all cameras, there is a color filter that sits over the photo sensor that only passes one color to each pixel. The camera's computer knows what pixels are behind the colors, so it takes the data and produces a color image. Your brain works in a very similar way. That said, our brains are much better at putting the world around us in context in terms of color. Most of the time, these differences show up when you are dealing with white light. Look at a white piece of paper under halogen lights, it looks white. Look at the same piece of paper under fluorescent lighting and it still looks white. Take the paper outside and it will still look white in direct sun shade and under cloud cover. The quote unquote white light is different in all these examples, but your brain is very good at sorting it out and interpreting the colors properly. As you have probably learned in primary school, white light is made up of all the colors in the visible spectrum. You can take white light and shoot it through a prism, and you will break the light apart into its pure colors. You can also take red, blue, and green light, combine them together, and your eyes, and probably most cameras, will see white light. Now, as I said, white light has more to it than red, blue, and green. It has all of the frequencies of visible light. The color temperature of white light depends on the balance of these colors. Modern cameras are quite good at determining white balance automatically. But, if it's set wrong, or your camera guesses wrong, white objects do not look white. If your camera has the ability to shoot in raw, you probably should whenever you can. I usually shoot RAW plus JPEG so that I can quickly preview my files with the JPEGs but still have access to the RAW files. With RAW, you have a direct dump off your camera's image sensor, and you have a lot more room to push things around in post-production without nasty artifacts showing up in the image. In a JPEG, the adjustments have been baked in, and then the compression chucked a bunch of that data out to make the files nice and small. When you make your adjustments in post production to your JPEG photo, you will have less room to push and pull the values around before those nasty artifacts start showing up. This might not be a huge deal, but then consider that you now need to re-save the image. This is going to apply another layer of compression, throwing out even more detail and data. JPEG isn't terrible, but RAW gives you far more options in post production. And when it comes to color, RAW is the better bet. So what happens when you have a situation where you have mixed lighting? That is lighting from two or more sources that have different color temperatures. Now things get really interesting. Let's look at some options. So in this example, I wanted to show you a few things you can think about and a few different ideas you can use to try and tackle situations where you have multiple lights with different color temperatures. So in this little illustration here, I've set up a little render, and I have some overhead lighting which is a little bit warmer in color temperature, probably closer to 4,000 to maybe 3,500 Kelvin. And then I have some windows over here to the left which are closer to daylight, probably around 5 to 6,000 Kelvin. The camera or the virtual camera in this case is set to daylight, white balance. So the light coming in from the windows looks pretty neutral and it looks pretty white when it shines on a white object. However, the overhead lighting looks pretty yellow. So if you had to take a photo in this kind of environment you have some color issues that you have to deal with here. So one way you can try and deal with this is to try and isolate the light sources. So maybe you can turn off all of the interior lights and work with the color of the light coming in through the window, whatever that may be. And so this would be your starting point for that. You can see by killing the overhead interior lights, now we just have the daylight color to deal with. Another thing you could try is closing down blinds or blocking the window light and dealing with only the light that's coming from the interior, any interior light fixtures. Now, one problem that you may run into is differences in the interior lighting color temperatures. In this little example here I have rows that are alternating between kind of warmer white or closer to 4 to 3,500 Kelvin, and then rows that are a cooler white, maybe closer to 5 to 6,000 Kelvin. And this is often times what you'll find in an office type situation where they have overhead fluorescent lighting, sometimes you'll have mismatched bulbs in the same light fixture, sometimes you'll have patches of daylight color or warmer white maybe around 4,000 Kelvin. Now, if we go back to just dealing with the window light and killing all the interior lights, one way you can make that look good is to add an additional light, some artificial lighting. Usually that will come in the form of a strobe or flash and without any modification usually strobes and flashes are around 6,500 Kelvin. They may be different between different models, but they're usually a pretty close match to daylight. You may have to gel it a little bit to match. So in this situation, I have the interior lights off, I have the window lights open, you can see on the ceiling here we're definitely are getting some light that's coming in from the windows. And then behind the camera I've positioned a virtual soft box to fill in the front of my little group shot of Lego guys here. Now maybe, you couldn't kill the interior lights and you couldn't kill the window lights. Another way that you can try and deal with this is to add some front fill flash that's somewhere in between these two lighting sources, and that's what I've done here. I've used a color that's not quite as orange as the overhead lights, and it's not quite as blue as the window lights, so it's just a little bit orange. But it falls somewhere in between these overhead lights and the window lights. And with a little bit of color balancing, which you can do in-camera or perhaps you can do that in post-production, you can get this to look pretty good. Now, the overhead lights and the window lights are never gonna look perfect, unless you spend a lot of time in Photoshop either one of them is going to look too orange, or the other one is going to look too blue. If we balance this exactly for the overhead lights, it's going to make the window light like really blue. If we balance this for the window light, it's going to make the overhead light look really orange. But you can get it pretty close on your subject and oftentimes that's the most important thing. So the few ideas that you wanna think about here is try and isolate light sources. If you can kill one of the light sources that's causing a color discrepancy, that's gonna help your colors to be evenly matched. Another idea is you can try and recompose the shot so that your subjects are a good distance away from both the differing color temperature lights. This will allow the light to basically mix and create kind of an average color temperature between the two sources, so that they're kind of evening out on your subjects, that's another great idea. Now sometimes you maybe able to swap light bulbs if you're in a situation where there's not very many lights and that may help to fix the situation. Now in this particular case, if this was an office building with this many lights, it may not be very practical but you can get pretty wide rolls of gel filter. And I've seen that used on the exterior of buildings to gel exterior light and get it to match interior lights. And that can be very effective as well. You can also try and gel interior lights but if you're dealing with a lot of lights like we are in our little virtual setup here that may not be practical. And then the other great option is to use some artificial lighting like strobes which can be extremely bright. And you can try an overpower either one of the light sources, or trying get it to mix with either of the lighting sources to even out your exposure and even out the color. You may not be able to control all of the background elements in terms of what color temperature light is hitting them when you're using strobes, but as long as you can dial in the color on your subject, that's gonna be the most important thing and that's gonna be the thing you wanna focus on. So those are a few ideas that you can use when you have to deal with situations where you have multiple lights with different color temperatures. You can also use color for an artistic effect, but that's a subject for another day. Brightness and color are critical to understanding light, but they're not the only characteristics that you need to understand. In the next lesson, you will learn about the contrast of light.