Regardless of the camera that you’re using, it’s important that your footage is exposed correctly. This all starts by understanding how shutter speed, aperture, and ISO work together. Also known as the exposure triangle. This is not a geometry lesson, but understanding how to dial in shutter speed, aperture, and ISO will help you nail that exposure every time. If you want to step up your game, it’s important to watch and understand this video.
Mastering the exposure triangle would not only affect the exposure of your image, but you can also change the look and feel as well. You could go as far as saying that you could dramatically change the appearance of your footage by changing one of the parameters in the exposure triangle. Because shutter speed, aperture, and ISO are linked, changing one of the parameters the two others will have to be changed accordingly to keep your exposure. The exposure triangle is a very common way within photography to describe the relationship between the three parameters. The triangle does not only apply to photography, but it also works with video even though it’s used in a slightly different way but the principles are the same.
Aperture is the iris inside the lens that determines how much light passes through the lens to the sensor. The size of the aperture is quantified by the f-stop or the f-number. A wide aperture where the iris is open has a low f-stop number leading to more light hitting the sensor. Opening up the aperture will help you in low light situations but changing the aperture will also change the look of your image as the depth of field changes. It’s very common to use a wide open aperture to separate your object from the background, like when you’re doing an interview where you want the person in front to stay sharp while the background is blurred. A narrow aperture where the lens is closed has a high f-number or f-stop leading to less light through the lens. A narrow aperture will help you on bright days where you need to close out some of that light to maintain exposure at a certain shutter speed. Closing the aperture will widen the depth of field so both foreground and background are in focus at the same time. Note most lenses are sharpest around F4 to 5.6. For the Mavic 2 Pro, it’s F4 but 2.8 is not bad either.
The shutter speed is the time that the sensor is exposed to light. With changing the shutter speed, we can change the look of the footage as well. With a fast shutter, we are able to freeze motion because we limit the time that the sensor is exposed to light. This is very useful if you want to capture motion in photography but with video, this is most of the time an undesired effect as this will make your footage look stuttery and jerky and not buttery smooth. With a low or slow shutter speed, we will start to see motion blur where the motion is smeared out as a result of the object is still in motion while the shutter is open. This sounds like a bad thing but it’s actually not as motion blur is natural to the eye and will make your footage look nice and fluent. You should normally strive to set your shutter speed into the double of the frame rate as this will give you the right amount of motion blur also known as the 180-degree rule. Slowing down your shutter too much will lead to an unsharp and blurry image even if your subject is in focus. So watching the shutter speed is not set too low is very important as you will not be able to recover your footage in post-processing. And this will happen regardless if your lens is image stabilized or not. Trust me I know that, I learned it the hard way. This side effect is often used within a long exposure photography to soften waterfalls or waves. It looks very cool and adds a very soft and creamy look to the image.
It’s commonly known as the sensitivity of the image sensor, but in reality, it’s an adjustment of the single gate for the post image. But for you and I, we can settle by considering this as a sensitivity. You’ll be able to shoot in very low light situations by increasing the ISO but you will at the same time introduce noise. The noise is normally seen as grain and will increase with the value of the ISO. When you have a wide open aperture and you have a shutter speed set to generate the right amount of motion blur, increasing the ISO is the only option you have to shoot in low light situations. Even if this introduces grain, this is better than sacrificing sharpness as a result of the shutter speed that was set too low. Denoising the footage in some post-processing software is a possibility and will definitely help improve the result. But in any case, you should aim to get the ISO as low as possible.
The EV value
Now we have all the three basic parameters sorted out for the exposure triangle you might have noticed on your camera there’s a value called EV or exposure value. This is the combination of aperture, shutter speed, and ISO and the value indicate in increments of one the changes that either doubles or halves the amount of light that hits the sensor also known as the stop. So if the value is minus one, your footage has been underexposed by one stop meaning half the light. And the other way around with plus one, your footage has been overexposed by one stop meaning the double amount of light. As an example changing the ISO in steps of 100, 200, 400, and 800, nicely matches the change in one, two, three, or four stops. The same logic applies to the shutter. So if you for example increase from one or 50 to one or a hundred, you will decrease the amount of light by one stop. Both ISO and shutter speed is probably easy to understand in relation to stops.
Aperture is a different story as there goes a lot more math into this but luckily we just memorize the f-stop sequence could look something like this. Going from F2.8 to 5.6 equals two stops leading to a quarter amount of light as we have halved it two times. This might sound a bit complicated but it’s actually not. By memorizing this sequence you will easily be able to jump between stops and you have the EV scale on your camera to help you if you’re in doubt. You need as a starting point to aim for EV value of zero to have your image correctly exposed.