Getting a new DSLR can be quite an overwhelming experience for a new photographer. All the knobs and buttons seem to do a thousand different things (and they do), but the dirty secret of photography is that, at its core, knowledge of the exposure triangle is what will make your new DSLR sing. If you know how the exposure triangle works, then you essentially know the basics of photography for beginners, and you can build your skills with the manual functions of your camera on that solid basis. Basically, you need to learn a few facts about aperture, shutter speed, ISO, and how they affect one another.
Having an exposure triangle chart can be really useful for learning!
Manual Control Over Aperture, Shutter Speed, AND ISO
The biggest benefit of having an advanced DSLR is that they allow manual control over most elements of the photographic process in terms of what's happening in the camera. But having that control is greatly beneficial if you know what elements you need to control and what they do. Let's look at the three essentials that make up the exposure triangle – ISO, Shutter Speed, and Aperture.
ISO – In film cameras, the ISO refers to how sensitive the film is to light. In a DSLR, the same concept applies, but it refers to the camera sensor (digital sensor) setting instead of film. The lower the ISO number, the less sensitive it is to light. If you are out photographing things in the bright midday sun, then you will probably want to use the lowest setting available (probably ISO 100 or 200). Conversely, higher ISO settings are in order if you photograph poorly lit scenes. Just remember that the higher ISO settings often bring the problem of digital noise (unwanted speckles and spots in your images). Usually, the top-end DSLRs are better at handling noise problems at higher ISO settings. The larger camera sensor is capable of handling low light better.
Shutter Speed – This one is fairly self-explanatory. Shutter speed simply refers to the time the camera shutter opens when you take a shot. It affects how much light enters the sensor. A shorter shutter speed (faster shutter speed) will result in less light hitting the camera sensor and will have the effect of “freezing” motion. A longer shutter speed will allow more light to hit the camera's sensor, and any movement in the scene will appear blurred in the direction it was moving (“motion blur”), which can often be a desirable effect depending on what you are trying to achieve. Each shutter speed setting doubles (or halves) the speed compared to the next setting. Don't forget to check out our beginner's guide to shutter speed priority mode on your camera.
Aperture – This refers to the size of the opening in the lens that lets light hit the sensor. Wider apertures allow more light in, and narrower ones allow less light in. The opening size is measured as f/1.4, f/2.8, f/4, f/5.6,f/8, f/16, f/22, etc. (commonly referred to as “f stops”). The small the number, the larger the opening, and each “stop” up from there effectively halves the size of the opening (and thus the amount of light entering the camera). Aperture also allows you to control the depth of field. Also, check out our beginner's guide to aperture priority mode on your camera.
The aperture also depends on the camera lens – prime lenses usually have a larger aperture than zoom lenses.
How Does That Work In Practice?
The three elements of the exposure triangle interact together. For example, reducing the shutter speed by a stop (increased light) and narrowing the aperture by a stop (decreased light) will result in an identical exposure. However, it may result in motion blur (due to decreased shutter speed) or a deeper depth of field (due to a narrower aperture).
ISO, shutter speed and aperture are collectively called the exposure triangle because they affect the exposure value. This is probably one of the most important technical concepts you can know in photography, and it's worth sitting down to learn (and standing up to practice) if you'd like to know how to use that shiny new DSLR (or any other camera, for that matter) to its potential. Simply put, learn to handle ISO, shutter speed, and aperture as well as you can, and your photography will improve a lot over time.