One of the first things new photographers are tasked with is learning about exposure and make sure they’re taking properly exposed images. Of course, things such as AUTO and priority modes make this a lot easier–even eliminating the need to know anything about exposure in some cases. But, being able to properly expose an image using nothing more than your own brainpower is something all serious photographers need to be able to do. As I’m sure you’ve heard before, being able to confidently shoot in manual mode will open the doors to your creativity and allow you to capture exactly the photo you envision.
Luckily, there’s this thing called the Exposure Triangle and it makes learning how to pull everything together to make a balanced exposure a lot easier to learn. Let’s take a look:
The Exposure Triangle
The exposure triangle consists of the three setting you adjust to set exposure. Now, many DSLR’s have a slew of other options that will assist with getting a perfect exposure (such as exposure compensation), but we won’t worry ourselves with those at this point in our photography journey. For now, the most important settings are: ISO, Aperture, and Shutter Speed.
You’ve probably heard all three of those terms at some point, but let’s dive a little deeper into their meaning and how they affect exposure.
When you are determining your ISO, you are essentially determining the camera sensors sensitivity level towards light. Using a low ISO, such as ISO 100, means the sensor will be minimally sensitive to light. Low ISO settings are typically used in high to good lighting conditions. When you are shooting in low-light conditions, raising your ISO, to say, 400 or 800, will make the camera sensor more sensitive to light. This allows you to use faster shutter speeds, even in low-light.
Because high ISO’s can introduce noise into an image, most photographers will try to shoot at as low an ISO as possible. That being said, this is becoming less of an issue as technology improves. Further, it’s always better to a shot, rather than no shot at all, so if push comes to shove, don’t hesitate to boost your ISO.
All lenses have aperture blades that open and close every time we push the shutter button, which allows light to pass through the lens onto the camera sensor and record the image we are shooting. The size of the aperture opening can vary from narrow to wide. This is determined by the aperture settings–often referred to as f-numbers. A small f-number, f1.8, for example, is a very wide aperture and will allow copious amounts of light pass through the lens. Small f-numbers can also drastically decrease depth of field, so be sure to keep that in mind.
Small apertures are useful for fast shutter speeds, allowing maximum amounts of light to pass through, and creating images with shallow depth of field.
A larger f-number, like f16, is much more narrow and won’t allow as much light to pass through. Large f-numbers also allow for more depth of field. Use larger f-numbers you need to use slower shutter speeds, it is too bright and you need to limit the amount of light that enters the camera, or when you need to maximize your depth of field.
The last point of the exposure triangle–but certainly not the least important–is shutter speed. Just as the name indicates, the shutter speed determines how long your exposure will be. For example, a shutter speed of 1/60th a second will result in the aperture blades (see above section) to stay open for 1/60th a second.
There are few reasons it’s helpful to be able to control shutter speed. Obviously to ensure your exposure isn’t too short or too long, but it can also be used to assist in shooting techniques such as panning (long shutter speeds) or freezing motion (shorter shutter speeds).
Tying It All Together
When you’re trying to decide on the best exposure settings, take the exposure triangle into consideration. When you’re just starting to learn, it may be best to think of yourself as a “priority mode”. First, you need to determine what is most important to your exposure. If you MUST have a shallow depth of field, you know you will need to shoot on a small f-number. From there, you can try out different ISO and shutter speed combinations until you have just the right look.
At first, this may take a lot of trial and error, but that’s a great way to learn. Just keep at it, and before long, finding the perfect exposure triangle for your shot will become more like second nature!