We’ve got this picture in our minds of a director holding her fingers up in twin L shapes, one inverted, and peering through the box they make, planning how to frame the shot. In the real world around us, there are three hundred and sixty degrees of information, and it’s the director’s job, along with the cinematographer, to figure out which very few degrees of that vista best help tell the story to the viewer. They do this, in part, by choosing different focal lengths of lenses to use.
The focal length of the lens will determine the shot’s field of view, or how much of the scene is captured in the frame. At their simplest, lenses are either “wide” meaning they show a lot of the scene, “normal” meaning things look about the size they do normally, to someone not looking through a camera lens and “telephoto” meaning things farther away look closer. Focal length is an important tool used in cinematography.
Depth of field: lens choice isn’t all about distance
The focal length of a lens produces several side effects that can work for or against a director, and one of these is exaggerating the depth of field or the out of focus areas in a frame. Wide-angle lenses minimize the out of focus areas, and normal and telephoto lenses exaggerate it. For more on this, check out this excellent video on understanding and mastering depth of field.
If you want your subjects to appear in front of a soft, out of focus background, choosing a normal or telephoto lens with a wide aperture is a good way to do it. If, on the other hand, you want objects in the background to also be in focus, a wide-angle lens with a smaller aperture is what you’ll want.
Zooming: Changing your focal length on the fly
Today’s sharp zoom lenses mean that you don’t have to be stuck with a single focal length; you can modify it to fit your needs. If the scene calls for 51mm or 48mm, you can do that, and you can also zoom in or out while you’re filming.
Usual lenses for unusual circumstances
Some lenses are extreme and they’re usually called “super” lenses — super-wide lenses show an unusually wide area and are useful for both sweeping vistas but also in very tight spaces, like a car or an elevator. Super telephoto lenses are good for bringing in action that’s very far away — whether it’s capturing a dancer on stage from the very back of a theater or a rooftop action fight sequence from another building, super-telephotos will help you get close.
The frame is your canvas
When you’re making a movie, you’re very much like a painter who shows viewers 24 or 30 canvasses every second. The makeup of each one of these is important, and your focal length will help determine which elements of your environment are visible.
When you look through your camera lens, ask yourself “what is this frame telling the viewer?” Be conscious of what you include and what you leave out. Ugly overflowing trash can behind your talent? Crop it out of your framing by using a longer focal length with a narrower field of view. Beautiful castle in the background? Is your subject a prince? Maybe add it into your framing with a wider lens.
When you look through your camera lens, ask yourself “what is this frame telling the viewer?”
Each element you include should add to your story and things that don’t help the story — and, “We’re in a beautiful place” is a totally legitimate part of a story — crop it out. Does having the mother of the bride in the background help tell your story? Get her in the frame! Does having drunken uncle Bob dancing with a vacuum cleaner? That’s for you to decide.
The crop factor
35mm cameras have been around since the 1930s and we’ve gotten very used to talking about lenses in their relationship to 35mm film, but not all cameras are the same. Depending on the size of the camera’s sensor, different lenses may cover more or less of the frame — meaning some of the field of view may be cropped out. This leads to what is known as the “crop factor” — how much of the image would be cropped off when compared to a 35mm film camera. Micro Four Thirds cameras, for example, have a crop factor of 2x, which means that the focal length of a lens is effectively doubled when you use it on a Micro Four Thirds camera body. A normal 50mm lens becomes a telephoto lens at 100mm, while a 28mm lens becomes a “normal lens with a focal length equivalent to 48mm. If that’s all too confusing, put it out of your mind for the time being — you’re going to learn that as you go.
One “must-have” lens
Zoom lenses are great, and a 24-70mm f/2.8 will cover many situations. But one lens that everybody should have in their kit is the venerable 50mm f/1.8. This lens is widely available, very inexpensive, and can provide some real “wow” factor if used properly. Its fast f-stop can make for really stunning close-ups when used in one- and two-shots of people, and it’s the one lens that can most easily give your video a professional look.
You need to be careful though. With that razor-thin depth of field, if your subject moves even an inch, they’ll be out of focus. This is where focus assist tools, and in particular, the Focus Peaking mode can help keep things sharp.
Start small, avoid getting overwhelmed
Especially with zoom lenses giving you every option from 24mm to 135mm in one package, picking your focal length can be daunting. Some filmmakers eliminate all that worry by sticking to the most extreme of basics. Cinematographer Sayombhu Mukdeeprom shot Luca Guadagnino’s movie “Call Me By Your Name” with just a single lens, a 35mm — slightly wider than normal. Likewise, cinematographer Yasujiro Ozu shot Jim Jarmusch’s 1986 black and white art film Down by Law with only a 50mm lens.
You needn’t be so extreme, but with so many choices, it may be a useful exercise to limit yourself to a very few focal lengths at first — 28, 50 and 85, or 28, 35 and 50 if you’re shooting indoors and have no need for a long lens. Try framing everything in one of those focal lengths. The benefit of having to change lenses between shots is that you become very much aware of the differences between focal lengths and will start to be able to see in your head (before a shot), which lens will work the best.
Your mission — should you choose to accept it
Pick a personal video project that you’ve always thought you wanted to shoot but never had the time to do and shoot it using only three lenses — or if you only have a zoom lens, three specific focal lengths on that lens. Try your shots with multiple lenses and observe the differences. How does the background look? Do you need to get closer or farther? Do things look cramped? Or spacious? Or Glorious?
Share your work and your thoughts with us in the comments below.