When it comes to using multiple cameras in a live environment one of the toughest things to do is to make those cameras images match. In fact, I was hesitant to write this article because it's something we have struggled with at my church for as long as we have had cameras. In the church world this problem is often exacerbated by that fact that in order to make budget many churches have cameras that span manufacturers, formats, sensor size and of course, quality. I know we have this issue, and I can't imagine we are alone in this. One of the other things that makes this especially tough, as we learned from the #thedress debacle (its white and gold by the way) is people see color differently. One of the first things you have to do when matching cameras is take the ambiguity out of the equation, this means using professional accurate testing gear such as a vector scope and waveform monitor. Many broadcast monitors now have built-in scopes and are great for this task. Along with the monitor you need some way to “paint” the cameras, such as a CCU (Camera Control Unit). This will allow you to adjust individual colors in the camera. Next, you are going to need a way to change the input going into you testing equipment, more on this later. The last thing you are going to need a color chart and a white card. Broadcast-quality color charts show known colors so that when you are balancing on them, the colors will fit neatly on the vector scope.
Testing devices can be expensive to add to an existing system. This is because you need a totally separate or split signal path that leads to the testing equipment. The good news is that many manufacturers take this into account when they build the cameras and usually provide another signal out. Sometimes this comes from the camera body and sometimes it comes from the CCU itself. A simple routing switch will suffice, but if you have a large production switcher the easiest thing to do is dedicated an aux from your switcher, this will save you a hassle with making a separate signal chain. Also main larger production switchers have aux controllers, which are totally separate interfaces, their main job is to select feeds independently from the program out, and they are perfect for circumstances like this.
Once signal path taken care of now you are finally ready to start matching the cameras. First place a white card where you are going to balance, ie where your pastor speaks. Then zoom all your cameras in to the white card and white balance your cameras. Many cameras will tell you what Kelvin temperature they are white balancing to, make sure these match. Once your cameras are all white balanced you can start color matching them by replacing the white card with the color chart. The testing gear measures different things; vectors scopes measure chrominance levels, so a black and white picture would shows up as a single dot representing the white of the picture. Contrast waveform monitors measure luminance values ranging from blackest black to whitest white. Looking at color chart in a vector scope should get you a double hour glass shape. Each point of this shape represents a color, if you imagine a color wheel super imposed over the vector scope graticule it starts to make a little more sense. Now, adjust the individual colors on the CCU until each point of the hour glass winds up in the corresponding box on the vector scope. Once you have done this lather, rinse, and repeat the process for the rest of your cameras. Once all your cameras are representing colors the same way they should be looking very close.
This is the point where having cameras of mixed manufacture and model will give you problems. Not all cameras render colors the same way, and there are lots of factors as to why, but you will see this in your vector scope. If you have the exact same shot in two different cameras you will notice the shape in the vector scope will be slightly different, and sometimes there is no way to make them match perfectly. One of the ways this manifests for our church is with the color purple; most of our cameras render purple as blue, and there is just no way to get all of our cameras to see purple the same way. But going through this color matching process should get your cameras match as close as possible --- and certainly much closer than just white balancing or trying to paint them by eye.
