If you don't already carry a gray card in your gear bag, you might decide to after this.
Achieving proper exposure is one of the first things you learn about as a fledgling cinematographer or photographer, but that doesn't mean that it's easy. There are different shooting scenarios that make it a much more tricky ordeal than many would expect it to be, which is why it's always good to know a few ironclad exposure techniques.
In this video, Adorama's David Bergman shows you how to use a simple 18% gray card, which many filmmakers use for color calibration and white balance, to achieve perfect exposure no matter what kind of shooting situation you find yourself in. Check it out below:
Though many beginners out there know about exposure tools, like light meters and scopes, many of them aren't aware that gray cards have uses other than white balancing and color calibration. There are several benefits to using these things as an exposure aid rather than other tools.
For one, the price is usually easy on your pocket. Depending on the size you get, you can pick one up for as little as $13. Second, gray cards of multiple uses. As I mentioned before, they can help you not only expose your images correctly, but they can also help you white balance, as well as ensure that your colors are as accurate as possible. Lastly, they're really easy to use. Just fill the frame (as best you can) with the gray card and use your camera's meter to get that line in the center.
Now, maybe you don't want to expose for middle gray. Maybe you're aiming for something more stylized and over/underexposed. That's totally fine! However, if you're looking for a good baseline from which to tweak your exposure, using a gray card to do it, or any other exposure tool for that matter, will certainly set you up to do just that.