Know Your Camera- Part 2: Gain/ISO-Aperture-Exposure
Gain, aperture and exposure are the three elements that together determine how bright or dark your picture will be. In addition to brightness, these three elements affect image quality, depth of field, and smoothness. Once you’ve recorded your video, you can make minor adjustments in post, but getting it right the first time produces the best results. In general there are some basic rules to follow.
- Gain should be kept low
- Aperture should be set to achieve the desired focus range
- Exposure should be kept at around 1/50 of a second
But rules are meant to be broken. Knowing how each of these elements works will allow you to make informed decisions.
Gain or ISO
- In low light situations, once you’ve opened up your aperture and lowered your exposure the only thing left is raising the gain.
- High gain in low light situations produces poor quality images.
- Some cameras have “native” ISO. So keeping gain at the lowest setting might not produce an optimal image.
- Aperture or Iris is a mechanical device inside the lens.
- Opening it up lets in more light
- A closed aperture keeps more in focus.
In addition to zooming in, wide open aperture narrows depth of field and produces background blur.
- Your videos contain between 24 and 60 still photos for each second.
- Each picture is exposed for a fraction of a second.
- An exposure of 1/48 or 1/50 of a second is standard.
- A higher exposure creates a sharper image with less blur, but makes movement seem choppy.
- Use an exposure of 1/120 or 1/180 if shooting for slow motion.
Setting all these controls may produce a perfect image, but sometimes in order to get the shot, compromises must be made. There are several ways to manipulate light outside of the camera so that these settings can be just right.
- Some cameras have threads on the lens. An ND or neutral density filter can be used to reduce the amount of light entering you camera. These are particularly useful on DSLRs. Most camcorders have built in gel filters that are used when gain is adjusted.
- Lighting is the best option in low light situations and should be used when time and budget allow.