Don’t let the fact that I am going to write a whole post here about focal length fool you. Focal length seems like it could be a little boring. It is probably the fact that it is measured in millimeters and sounds all “mathy!” But knowing a little about it can help you use and choose your lenses wisely.
What is Focal Length?
In easy terms, focal length will determine how much of the scene in front of you your camera will see and be able to photograph. It is referring to the numbers on your lens that might read something like this: 18-55mm, 55-200mm, 50mm, or 35mm.
Some words you might hear related to focal length are “wide-angle” or “telephoto.”
“Wide-angle” refers to focal length numbers like 18mm and 24mm—the smaller numbers. These focal lengths will help you take in a large sweeping scene. They are great for architecture or landscapes, but not flattering for people because they tend to distort things and make them look wider. When was the last time you wanted to look wider or larger than you really are? Never? I thought so!
“Telephoto” refers to focal length numbers like 85mm and 200mm—the larger numbers. These focal lengths will narrow how much of the scene your camera takes in and help far away things appear closer. Most people call this “zooming in” on your subject because though you may be far from your subject, they can fill your frame. Pretty much everything between 85mm and 200mm would be considered a telephoto focal length!
Telephoto focal lengths are great for wildlife, sports, and portraits. These lenses are nice for portraits because they tend to distort in the opposite way that wide-angle lenses do–smaller and thinner. When was the last time you wanted to appear smaller or thinner? This very second? I thought so ;)!
Zoom vs. Fixed Focal Length Lenses
Zoom lenses allow you to use a variety of focal lengths with just one lens. If you are using an 18-55mm lens, you can use any focal length between those numbers while standing in one spot to change the scene that fills your viewfinder. However, most zoom lenses limit your widest aperture significantly to either f/3.5 or f/5.6.
Fixed focal length lenses only allow you ONE focal length. When I use my 50mm lens, I can ONLY shoot at 50mm. If I want my subject to appear closer and fill up my viewfinder, I have to actually MOVE closer to them with my feet. However, these lenses offer the widest options for apertures. Even the cheapest of these lenses generally give you a widest aperture of f/1.8!