F-stop
An f-stop is a unit of measurement for aperture, which is essentially the size of the hole that opens up in your camera when you snap a picture. Different apertures can increase or decrease your depth of field, which is the amount of your shot that’s in focus.
F-stop measurements look like this: f/2.8, f/4, f5.6, f/8 and f/22, with the smaller the number meaning the larger the hole. The larger the number, the more likely the entirety of your image will be in focus (the foreground and the background, while only the foreground will be in focus for the lower numbered apertures.)
Learning more about and playing around with your f-stop numbers can help you gain more control over the depth of field in your videos.
ISO
ISO refers to the film speed of a camera. In photography, this measures your “film’s” sensitivity to light. The higher your ISO, the more noisy and grainy your photographs can look.
ISO measurements can begin at 50 or 100 and continue all the way into the thousands in varying increments. It’s recommended that you play around with your own ISO settings to get the best understanding of how changing these settings can affect your video, but this video also offers some great examples of how different ISO levels affect video
Level Indicator
The level indicator is a meter you can see in the viewfinder of your camera and looks like this:
-2..-1..0..1..2
These are exposure level indicators that allow you to control whether your picture is underexposed (too dark) or overexposed (too light). If footage is too dark, the level indicator can be moved to the right, to the more positive numbers. If the footage is overexposed during filming, you can similarly move the meter towards the negative numbers on the left to darken it.
If you’re new to digital photography and videography, this is a great video that can help explain the basics of aperture, shutter speed and ISO