Understanding the uses of Aperture and ISO for Video
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Hey everyone! Last time we talked about what framerate and fps meant in the context of shooting video on your camera. I hope that was clear to folks. This time, we are going to look at two other elements that impact the success of your video, being your choice of aperture and ISO. At this point, we know that our shutter speed is fixed and does not change, as we learned last time.
Aperture
When we shoot stills, we think of aperture as having two roles, determining the amount of light passing through the lens to the sensor and determining the amount of depth of field that we obtain. When we get to video, while the aperture still controls the amount of light passing through the lens, the only really important decision here is how much depth of field that will be obtained.
Whether you are shooting a traditional DSLR or a mirrorless body, video is shot in some form of Live View, so you are seeing exactly what the sensor is seeing. This is a massive benefit because it also means that you are seeing the amount of depth of field that you are going to have in your recorded video. Consequently, we select the aperture based on the required depth of field. For very shallow depth of field we will use a wider lens opening and for more depth of field we will use a smaller lens opening. If you are believing that for this level of full control, that the camera is in Manual mode, you are 100% correct.
You may also be saying at this point, that you think the overall image is too dark or too light and are starting to wonder what to do next. Perfect! This takes us to our third and final setting, the ISO
ISO
Video in actuality does not really concern itself with ISO. Technically it concerns itself with what is called Gain. If you’ve played an electric guitar, you may have seen this term before, and it’s not quite the same so for video, start with a clean slate. Gain is the control of scene brightness and in our DSLR and mirrorless cameras we control this via the ISO setting.
Some of you may now be worrying about digital noise. Fair enough, but because we will have multiple frames every second, noise is less noticeable, particularly if there is something happening. Now if you shoot sixty minutes of a rock on the ground, just before the viewer abandons your video, he or she may start to notice digital noise if the light level is very low and thus the ISO is very high, but in practical reality, its not an issue. There are tons of very acceptable videos shot on rather slow smartphone lenses and so at higher ISOs and virtually no one complains. Other than those folks who pixel peep video. Don’t worry about digital noise.
Creative filmmakers will alter the gain level to create mood, shooting a darker clip, or a brighter clip to create mood. In this case, you are setting the ISO for each clip. It’s easy to do. Look at the live screen and alter the ISO to achieve the look you want.
However, if you are starting out and just want a good overall exposure for all your clips, set your camera to AUTO ISO. This will cause the camera to shift the ISO (gain) level to produce an even exposure regardless of light levels within the camera’s ability to capture information. This option is the easiest and removes one thing to worry about, and remember, you are going to see what you will get on the live display while you are shooting. It does not get any simpler.
Now you know how to use the three key elements of shooting video and they are really quite easy to figure out. Time to pick up your camera and go shoot some video! Video is a different thought process from shooting stills, but just because you’ve not done it, does not mean that you cannot do it. Once upon a time, you didn’t know how to shoot stills either.
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I'm Ross Chevalier, thanks for reading, watching and listening and until next time, peace.
