Why do I need a monitor? The three-inch screen on the back of your camera seems big, but when you're using it to focus, review footage, compose and handle just about every other part of the video-making process, it can be limiting. You can get a wide variety of external screens, most of which attach to your camera via HDMI. The extra screen real estate will suck up battery power, but it will give you a much clearer view of what your shots will look like. If you have a loupe for your LCD screen, this might not be as crucial, but every shooter has their preference. Do what your eye and your budget tell you.