For low light photography, familiarity with the exposure triangle teaches one that there are three things you can do to help your camera’s sensor catch more of that all-important light needed to make an exposure. They are: open your aperture wider, raise your ISO, and slow your shutter speed. You’ll sometimes have to use a combination of all three for scenes with very low light.

Now, apertures only open so wide, and sometimes you’ll still be thinking about a desired depth of field, so if you’ve made a decision on aperture, assuming no flash is being used, that leaves two legs of the exposure triangle to adjust. So, how do you decide whether to rely more heavily on high ISO or slow shutter speed?

Adorama TV has made a video to help photographers get a grasp on the concepts of high ISO and slow shutter speed and when it makes sense to utilize each. In the video, Mark Wallace takes a Leica M10 out for some night photography to illustrate when and why to choose each option.

If you’ve struggled to grasp why you would choose one over the other, this video will provide a clear picture. Simply put, whether or not motion is desired is the most significant determining factor, as well as how well your camera can handle high ISOs and how clean the image needs to be.

[Rewind:] The Basics of Shutter Speed, Aperture, & ISO | Minute Photography

To test your own camera’s high ISO capabilities, you can take images at progressively higher ISOs and analyze the results in your photo editing software. Older cameras are going to show their age here, and smaller sensors will usually underperform with higher ISO’s.

In newer cameras, full frame generally still has an edge, but smaller sensors are closing the gap. There are many APS-C cameras that have very usable high ISO ranges, like Fuji’s excellent line.

Check out Adorama TV’s video below to see Mark Wallace break it all down.