ISO- This changes the sensitivity of the film, the lower the ISO the less sensitive the film is and the more light you’ll need. So then obviously vice versa, the higher the ISO setting the more sensitive the film is the less light you’ll need.
If you were filming outside in the sunshine you would have your DSLR set to an ISO of 100-400, if it was low sunlight outside you would have an ISO setting of 800.
For evening use or low light you would have an ISO setting of 1000+
Aperture- this changes how wide the lens is. The higher the aperture setting the wider the lens is meaning it allows more light in so the image is more blurry. The higher the setting the smaller the aperture of the lens therefore the less light can get in and the image is sharper.
Shutter speed- affects how much light gets into the camera and for how long. Low shutter speed captures moving images as still. Open the shutter for a small amount of time and you can freeze a moving picture. Opening the shutter for a long time can show the movement of a fast moving object.