ISO and gain are used for very similar things. The difference? Well it depends on whether or not your camera has one or the other, or in some cases, both.
Most dslr – mirrorless or with a mirror – tend to have ISO settings. Gain is typically found on cameras that are for video purposes only.
What is it though? Well the answer is somewhat simple. ISO and gain are used on cameras to help add more clarity and light into a video, or even photo, in a dark environment.
When you do it manually, you can change the settings. For ISO, most cameras have a setting from 200-6400. If your camera doesn’t get to 6400, it will at least make it to 3200. ISO settings can be adjusted regardless of how dark an environment is. When you white balance, some cameras will automatically set your ISO to the best setting – you can always adjust it manually – and it will sometimes be high even if it’s a light day out, or overcast for example. In these cases, you might not see any real noise, and that’s primarily due to the fact that there’s natural light so it’s not effecting the video in the same way.
For the sake of this post, I’m focusing on ISO in dark environments.
For gain, most cameras go from 0db to 12db. “db” refers to decibels which is the level in which your gain is at and the signal that it sends out from the camera. I could get more technical, but I think it would become relatively confusing. So for now, just understand that “db” is decibels and as you raise it, the more noise you have in the shot. You can go higher that 12db, but you risk getting a considerable amount of noise, but if the environment is really that dark, then you must do what you must do.
The only problem with filming in a dark environment and raising the levels for gain and ISO, is that your video, and photo, will receive a lot of “noise”. Noise is all the little grainy spots that appear on the video and photo.
It’s a handy tool that will lighten everything up, but it won’t appear crystal clear as perhaps something better lit.
Here is a video as an example. You’ll see the different ISO levels and how it effects the video in a dark environment, and in the video the “noise” is pointed out. Don’t worry about audio, there isn’t really much to it.
Summary: ISO and gain can be turned up in order to allow clarity of the shot you’re taking. It is typically only raised high in dark environments and when raised, it will increase the amount of “noise” in your shot. ISO can also be used in different lighting environments though and when you white balance, it will automatically adjust the ISO setting to accommodate. In this case, you might not get any noise because you’ll have proper or better lighting. It is only when you set the ISO high in a dark environment, or low light, that you will start seeing noise develop.
Note: You can see the noise a bit better when you maximize the video. Watching it small, it’s not quite so obvious.