If you’ve ever been confused by the term “focal length” and what that means when it comes to choosing a lens, worry no more. In this tutorial, we will break down what focal length is in simple, easy terms, so that you can make informed decisions on what lens is right for you.
What is Focal Length?
Focal length is represented in millimeters (mm), and tells us the angle of view for a given lens, or how much of a scene will be captured using that lens. For all intents and purposes, the focal length is how “zoomed in” your images are. The smaller the focal length, the wider the field of view. The higher the number, the more narrow (or “zoomed in”) your field of view will be. You can see this demonstrated in the images below.
Which focal length should I use?
Which focal length to use will depend on what you are photographing, your personal style, and the look you want to achieve. While many landscape and architectural photographers prefer wider angle lenses, many portrait photographers prefer lenses that are a 50-200mm focal length. Wide angle lenses allow for capturing more of the scene, while longer lenses allow you to zero in on your subject.
The image below was taken with a 16-35mm lens, at 16mm.
I prefer to use either a 35mm or 50mm lens for my indoor lifestyle photography work.
The 35mm is also a great choice for larger groups, or capturing more of the environment in your portrait sessions, as seen in the images below.
Lenses from 50mm to 200mm make excellent portrait lenses, and there are varying benefits to each of the focal lengths within this range. 50mm lenses are great because they “see” similar to the naked eye, and provide a very realistic field of view to the photographer. They also allow you to shoot within a close proximity to your subject, making it easy to give direction and communicate with them.
The 85mm lens is an excellent choice for portraits as well, so much so that you can read our reviews of the Canon version here, and the Nikon version here. This lens takes amazing photos and the longer focal length gives you some awesome bokeh and lens compression.
The 135L and the 200mm focal lengths are also fantastic for portraits. The long length of these lenses is very flattering to facial features, as these focal lengths have minimal distortion.
Focal Length Crop Sensor Cameras
A crop sensor camera, as the name implies has a smaller or “cropped” sensor than it’s full frame sensor counterpart. The most noticeable impact associated with this is what is called a “crop factor”. The crop factor refers to the magnification of field of view when looking through the viewfinder. For most AP-C and crop sensor DSLRs the crop factor is 1.5 or 1.6, so for easy math, lets use 1.5 as the crop factor.
An example of the crop factor – a 50mm lens on a full frame sensor camera will have a field of view of 50mm. A 50mm lens on a crop sensor camera has a field of view of – 50mm x 1.5 crop factor = 75mm. So in lamen terms, your 50mm lens will “feel and act” like a 75mm lens when on a crop sensor camera. Read more about Full Frame vs. Crop Sensor cameras here!
Focal Length & Lens Compression
Longer focal lengths (higher numbers) cause compression. Compression is a phenomenon produced by longer focal length lenses in which the background seems to be flattened out and pulled closer to a subject. Lens compression can enhance the bokeh and background blur in your images, making it ideal and sought after by many portrait photographers. You can read more about how focal length, lens compression and bokeh are all connected in this article.
Choosing the “right” focal length will depend entirely upon what it is you are trying to capture (landscapes, lifestyle, portraits), as well as your personal style. To find the focal length that is right for you, we suggest experimenting and trying out different lenses until you find the length that suits you and your shooting style best. Who doesn’t love to try out lenses anyway? Have fun with it!