Video Tech Tips - Aperture

What aperture is and how it works with ISO and Shutter Speed
Jul 19, 2016

Hi, this is Wade James, and thanks for checking out Guidefitter's Video Tech Tips. We started with ISO, we went to shutter speed, here we are at aperture. So basically, aperture is how open or closed your lens is. The more you open the lens, the more light you introduce into the camera sensor. Now you'll notice depth of field.

Say I'm running my lens at f/1.8, I could have my nose in focus, but my ears be out of focus. Usually having your lens wide open creates awesome b-roll shots. So you could pull focus from a piece of tree to a different piece of bark, or from a branch to your face. So running wide open allows you to do this because it give you that shallow depth of field as they call it. Now when you close your lens off, it makes things darker. And by making things darker, it opens up your depth of field. So instead of having that shallow depth of field, I could have my hand in focus and the background in focus at the same time.

The take off with this is knowing how to run your aperture, your ISO, and your shutter speed to get that look you're going for. So say I'm doing this b-roll shot and I want to have a pull focus, which is pulling focus from one area to another, closer or farther away from the camera. Say I'm on this log and I want to pull focus from the far end of the log to the close end of the log. I'll have my ISO as low as I can. I'll have my shutter speed where I want it for my frame rate that I'm shooting, and then I'll have my lens wide open. Uh oh. Say it's too bright, now I'll jack my shutter speed up to get it exposed where I want to. To leave that glass wide open so I can still get that shallow depth of field so you can really see the focus come from the far object to the close object. Running b-roll and getting alternate shots, I usually always run my lens wide open.

When I'm in the stand and filming an animal coming in, I don't want to have to worry if my focus is off. So what I'll do is run my aperture around f/8 minimum. That still gives me a good shallow depth of field, but I don't have to worry about focus being as finicky. Now let's say worst case scenario, I'm running my lens wide open at f/1.4, I'm running my ISO at 100, and say it's so bright that I have my shutter speed set at 1/8000th and I can't get it any darker. Now is when you'll notice you need to start sacrificing how wide open your lens is to get things properly exposed. Try going to 2.8 or 4.0. These will all help you get the image properly exposed, and usually still be wide open enough that you can get a good depth of field. My best advice for you is just to go out and screw off with your camera. Figure out what ISO range works best for you. Figure out how shutter speed works. This is trial and error. I have no college education on this, it was all just trial and error. So get out there, run your camera, make mistakes, and find out how it works and how to make it work for you.

My name's Wade James. Thanks for checking out Guidefitter Video Tech Tips and keep on shooting manual.