Understanding camera lenses and how they influence your image is filmmaking 101.
In this article, we explore the main features of camera lenses and which lens to throw on your camera to capture your shot in the best way.
Focal Length
Focal length is the basic description of film camera lenses. It’s how photographers usually call their lenses by (“Could you pass me the 50mm, please?”). Focal length indicates the distance in millimeters from the focal point (the point where your image appears to be sharp) to the sensor of the camera.
Focal lengths typically range from 10mm to +800mm. 10mm-24mm is considered super wide-angle, 24mm-35mm is wide-angle, 35mm-85mm is standard, and 85mm-400mm is tele. Beyond that are the more specialized super tele lenses.
Your choice of focal length will depend on how near or far you want your subject to appear in the image (magnification), and how much of the scene you want to include (angle of view). Most beginners will choose a wide-angle lens for landscapes to include as much of the scenery into their image as possible. They’ll reach for their super tele lens to capture wildlife so they can zoom in without having to come physically too close to their subject.
However, this rule is not set in stone. You need to understand how different focal lengths behave. Have you ever shot a landscape that seemed impressive to your eye, only to be disappointed with how it comes out through your wide-angle lens? That’s because wide-angle lenses tend to make things look smaller. Switching to a longer focal length might improve your composition.
Another side effect of wide-angle lenses is the distortion of close-by objects. Walls near the edge of the frame are curvy and people’s faces tend to show big noses, chins, or foreheads. Unless you aim for a comical effect, wide-angle lenses are usually not fit for portrait photography. The sweet spot for portraits starts at 85mm. One of my favorite portrait lenses is the relatively cheap Canon 100mm Macro lens (yes, macro can do more than shooting insects and flowers).
Aperture (Lens Ratio)
Another important consideration is the so-called speed or aperture of the lens. Aperture indicates the size of the opening through which light enters the lens and is expressed in f-stops which you can usually find as a ratio at the front of your lens barrel (e.g., 1:2.8-4). You want your lens to be as fast as possible, meaning the aperture number should be as low as possible and constant. Up to 2.8 is considered a fast lens. The trade-off is that fast lenses with constant aperture are usually much pricier and heavier (The aperture in cheap lenses usually increases automatically as you zoom in).
Fast lenses perform better. They handle low-light conditions better, they create a much more pleasing shallow depth-of-field (that creamy, blurry background effect photographers affectionately call “bokeh”).
You might be lucky enough to own an f1.4 lens, but that doesn’t mean you should constantly leave your lens at 1.4. The point is to have as wide a choice of aperture as possible so you can tune into a perfect opening for your shot. If you want to tack sharp images, then increase the aperture by 2-3 stops to find your lens’s sweet spot. Increase your aperture between f8 and f11 to obtain sharpness from foreground to infinity. Bump your aperture up to f18 or f20 to create a cool star effect around light sources. And if you want that buttery smooth bokeh, then keep that aperture wide open and step closer to your subject.
Prime vs. Zoom
Choosing between prime lenses (lenses with a fixed focal point) vs zoom lenses is a question of trade-offs. Prime lenses are often cheaper and produce better image quality than zoom lenses, but it does mean you’ll have to put in more leg work. Since you can’t zoom in or out, you’ll have to physically move to get the same composition. Sometimes that’s not an option, which means you’ll miss the shot. Another disadvantage of prime lenses is that you’ll spend more time swapping lenses, which does get tiresome after a while. Still, many top photographers swear by prime lenses for their image quality.
Other factors such as your camera body (full-frame vs crop sensor) can also influence your lens choice, but that will be for another article. The point here is to never get lazy. Use the right lens for your image. You can’t correct a bad lens choice in post. Happy shooting!
