So, you’ve been practicing dialing in your shutter speeds and aperture on your camera and now you’re back for more. Great, because today we’re going to cover the final element of the exposure triangle: ISO. The final step to becoming a manual photographer involves utilizing the three manual functions of your camera in unison to capture a perfect exposure. This might all sound a bit overwhelming, but don’t worry too much. Luckily, your camera has nifty little tool to help you with that as well!
So, to start, what exactly is ISO? ISO actually originates from the days of film photography. It essentially measured your specific roll of film’s sensitivity to light. This affected what conditions you could use your film in. For example: A high sensitivity film roll would suite night photographers best, where a low sensitivity film might not capture enough light to produce a proper image in a dark setting. A range of different ISO rolls once flooded the market:
You might be asking, “Why so many different types of film? Why not always use a high ISO film? One could then shoot in both dark or light situations.” While that is true in theory, there is one disadvantage to high ISO film. The more sensitive a film is to light, the more grainy an image it produces. Often, shooting at extremely high ISO settings results in grainy images that look as though they’ve had a crappy Instagram filter applied, as you can see below:
The same holds true for digital photography, however ISO on your DSLR is digitally adjustable. Much in the same way film works, the ISO setting on your digital camera adjusts the image sensor’s sensitivity to light. Modern DSLRs offer a range of settings to play with in the varying lighting conditions you might encounter when you are out shooting. So, a general rule of thumb is to shoot at the lowest sensitivity possible to reduce grain.
But how do you know what all these settings will produce? If you take into account shutter speeds, aperture, and ISO, that’s a lot of trial and error to experiment with, right? Not quite so; All film SLR and modern DSLR cameras have a nifty, built-in light meter. This generally appears at the bottom of your viewfinder when you look through the eyepiece. This meter has a needle that will shift from left to right as you tweak camera settings. The goal is to get the needle dead-center on the meter as is seen below. This indicates that your camera will produce a properly exposed image given your current lighting conditions.
The go-to settings you want to tweak first are aperture (learn more) and shutter speeds (learn more). When these settings fail to produce a properly exposed image, you may have to resort to lowering or raising your ISO to get the light meter as close to center as possible. With that said, always remember your camera is just a machine. It uses sensors and programming to predict which settings will look best. But photography is highly subjective. At the end of the day, you are the photographer. Rules are often meant to be broken and only you can decide what settings will produce a desired outcome.
That’s really all there is to it! Okay not really, there are hundreds of other settings and sub-menus you can dig through in your camera’s settings. Just look at the massive manual that came bundled with it! Because DSLRs vary from make and model, I recommend reading through it to familiarize yourself with your camera. However, the fundamental settings I covered in this Manual Photographer series are universal and serve as the foundation for manual photography. Every other setting your camera has builds upon these fundamental three. Now that your well-equipped, it’s time to practice. The best way to hone your skills is to get the heck out of the house and start shooting!