Focal Length: An Easy Guide to Using and Understanding Camera Lenses

1.1 FOCAL LENGTH ESSENTIALS

The basics of lens focal length

Your camera and lens are the audience. Your audience sees no more and no less than what you show them. It is crucial that when telling your story, you consider all the aspects of visual storytelling for your film.

All the small creative storytelling choices that you make for each image of your film are important. These small choices coalesce into the powerful effects your audience will feel as your story unfolds before them.

Focal length affects how "zoomed in" an image appears. The higher the millimeter (mm) number, the more "zoomed in" the image appears.

Focal length is measured as the distance from the focal point where light rays converge in the lens to the sensor or film in the camera, as illustrated in the diagram below.

Your shot begins with the focal length of your lens. Here's a more detailed focal length meaning:

“Which size lens do you want to shoot this with?”

At times you may hear someone use the term lens size, which is the same thing as the focal length. Very rarely will you hear someone respond to the question with something general like standard lens or long lens. More often you will hear the specific mm value.

When it comes to narrative filmmaking, your focal length will allow you to capture footage with different visual properties based on your lens choice.

There are both practical and creative consideration when making these decisions, so understanding focal length might be the most important visual tool for a director to comprehend.

A longer focal length, such as 135mm or 85mm in the diagram below, results in a narrower angle of view and greater magnification. Meanwhile, a shorter focal length, such as 24mm or 14mm, translates to a wider angle of view and less magnification.

In this first example, below, the camera is positioned the same distance from the subject and different lenses are used:

In the next focal length example, the camera is positioned at varying distances with different lenses, as indicated in each photo:

So remember:

The lens mm number refers to the focal length or magnification. This can also be casually referred to as the lens size.

In StudioBinder, you can easily select the lens' via your shot specs column. Take a look below to see it in action:

Before we get into the different focal lengths, take a minute to download our FREE Ebook — Camera Lenses Explained Vol. 1 — where cover everything you need to know about the different types of camera lenses, their unique visual characteristics, and how to use them.

1.2 Lens FOCAL LENGTH

Wide-Angle Lens (23mm-35mm)

A wide-angle lens is any lens with a set focal length that is shorter than the length of the sensor or film (measured diagonally). For a full frame sensor, your wide-angle focal length would be anything below 35mm.

Often any lens with a focal length that falls between 23mm and 35mm can be categorized as a wide-angle lens. To go down any lower than 23mm would still be considered wide-angle, but it pushes the lens into fisheye territory.

1.3 CAMERA FOCAL LENGTH

Standard Lens (35mm-55mm)

A standard lens has a set (prime) focal length that is around the same length as the sensor or film (measured diagonally). For a full frame sensor, your focal length would come in right around 42mm.

Often a lens falls between 35mm to 55mm can be categorized as “standard” focal length.

1.4 FOCAL LENGTH comparison

Long-Focus Lens (55mm-500mm)

A long-focus lens is any lens with a set focal length that is significantly longer than the length of the sensor or film (measured diagonally). For a full frame sensor, your focal length would be anything above 55mm.

Often any lens that falls between 55mm to 500mm can be categorized as a long-focus lens. You may hear a cinematographer or camera operator refer to them simply as "long lenses."

Some long lenses are also telephoto lenses, but this only occurs in a specific situation where a telephoto group of glass is built inside.

Telephoto lenses are often used to shoot wildlife or sports. They can make distant subjects appear closer. Also, in close-up portrait shots, telephoto lenses tend to keep a subject's features in  proportion, with minimal to no distortion.

1.5 FOCAL LENGTH explained

What is field of view?

Field of view is the amount of space you see on the image plane. It's how much of a scene is captured in your image.

If you were to record footage of your hero actor:

A wider lens might show the torso, which is a larger field of view.

A longer lens might show only their face, which is a smaller field of view.

To expound upon what we've discussed in section one above, a lens with a shorter focal length (i.e., a lower mm number) gives you a wider field of view. A lens with a longer focal length (i.e., a higher mm number) gives you a narrower field of view.

This diagram illustrates the principle:

Some films are shot entirely with wide or long lenses because of the type of images they create, and in other cases directors will elect to show a gradual change in a story through a gradual change in focal length.

Check out the video below to see how DP Roger Deakins chooses which lens to tell a particular story in every shot.

Focal length might seem like a purely technical consideration, and there's a lot of detailed mechanics involved. But as the video makes clear, technical details like focal length and lens selection exist to serve your story.

An understanding of focal length, field of view, and lenses gives you the power to orchestrate your shots and convey intended emotion. This is what we'll explore further in the next chapter.

2.1 short FOCAL LENGTH

Compress Space

Longer focal lengths compress the image by causing the background to appear closer to the subject. This compression also causes objects (or actors) that are behind one another to appear closer together than they really are.

In essence, you can create a shallow depth of field and "flatten" subjects and their background by shooting from a distance with a longer focal length lens. This is a form of distortion known as lens compression.

You can compress space to achieve the following results.

Build suspense

This clip from Tinker Tailor Soldier Spy is a highly exaggerated example since they used an incredibly long focal length of 2000mm. Most long telephotos commonly used top out at around 300mm.

This video highlights that a long focal length can be used for interesting creative applications, such as creating a sense of danger within this scene.

However, it also fills a practical application by manipulating perspective and allowing dangerous special effects, action sequences, or perhaps landing planes to be further than they appear, eliminating risk for actors.

Create intimacy

Another lens compression application is to make two characters feel closer, and therefore the shot more intimate, such as in this scene from The Office.

If you look at the difference between the two shots in the scene, the ones with the longer lens make Holly and Michael feel much closer, which is appropriate in context.

In this shot, Michael is reconnecting with Holly. They are just friends now, but he’s trying to woo her. This shot establishes the scene, but also has some level of intimacy — as you might have noticed, the filmmakers used a long focal length to isolate Michael and Holly and drown out other distractions — their interactions here are the focus.

The filmmakers continue using a long lens here, which makes Holly and Michael appear even closer than they did in the previous shot. It’s a very cozy image. In the final shot, the filmmakers zoom in even closer. Note the blurred background.

It appears that Holly and Michael are shoulder-to-shoulder. The intimate moment, and Michael’s intent, is sold with the way he looks at her when she’s grabbing and eating her strawberry.

If you watch the scene, it’s clear he’s still in love with her. The shot helps visually communicate this information to the audience.

Become a voyeur

Longer focal lengths isolate a subject from the background. This perspective is very different from how we normally perceive the world.

Because of these effects, a longer lens can create the sense that a character is being spied on (especially when combined with other techniques).

This can be literal, or done so the audience has a sense that they’re watching a private moment.

In this frame from the short film Sacramentum, a combination of techniques give the feeling that something secretive is going on.

Specifically, a cultist has dragged a man into the woods to sacrifice. Looking down at the unconscious man from above (like a security camera), with a long lens (like binoculars), and with objects in the foreground (as if someone is watching), all enhance this feeling.

2.2 long FOCAL LENGTH

Expand Space

Wider focal lengths exaggerate the appearance of distance between objects. In other words, they actually take the normal perspective you have that objects become larger as they get closer, and smaller as they get further, and intensify this difference.

Use wide focal lengths to do the following.

Enrich setting

Here's a buzzworthy example of wide-angle lenses expanding space. Watch the trailer for The Favourite below, and count how many times wider focal lengths (and even fisheye lens shots) enrich the world of early 18th century England.

The far objects appear even smaller, and the closer objects even larger, than they would normally appear to the human eye.

This includes causing backgrounds to appear further away compared to normal and long focal lengths. This is often used for landscape and architecture as it enhances the existing shapes and leading lines of the image to create visual interest.

Isolate characters

Since wider focal lengths exaggerate the size of things close to frame, this can give the audience a sense that they are right there next to your character, up close and personal.

It’s a more objective perspective for the audience to experience because this perspective is like sitting next to a friend.

Using a long lens would have flattened the features on his face, giving the audience the impression that they are watching him from afar, as opposed to experiencing events with him.

2.3 FOCAL LENGTH: CREATIVE TOOL

Capture Action

Longer focal lengths exaggerate lateral movement. That is, movement perpendicular to the camera will be intensified by increasing the perceived speed of a subject compared to its background.

Why is this?

Reason number one is that due to compression of space with longer focal lengths, the subject in the frame appears to be moving more rapidly against its background.

We can’t explain this much better than by showing you this great scene from Fast & Furious. The filmmakers use this lateral action technique throughout the film, but there are some great examples in this particular scene. 

The other reason is that due to the magnification of longer lenses, even the slightest movement by the camera operator can be greatly exaggerated. Combined with visual compression, this results in camera shake which can be a desirable effect that creates a sense of urgency and energy.

However, it is easily overused and can be too disorienting for the audience if used excessively, so keep this in mind.

2.4 FOCAL LENGTH in motion

Exaggerate Movement

Wide lenses and shorter focal lengths increase the perception of speed when a subject is moving toward or away from camera.

This is a sort of side effect from the fact that wide lenses exaggerate the distance between objects. Since closer objects appear larger, the wider your lens, the more quickly an object grows in the frame as it approaches.

This increases the perception of speed when something moves away or toward camera. Since wide lens exaggerates distance to camera, to create more intense effect of moving toward or away from camera, you need to use a wide angle lens.

A secondary effect of wide lenses is that they minimize the perception of camera shake, thereby smoothing out your shot.

Wide lenses can be used to exaggerate the following.

Speed of characters

Foot chases are again a great example of how to use wide lenses to your advantage. If you’d like to show the baddie chasing your hero through a hallway, you can make their movements appear faster than they are by using this technique.

This not only makes the scene more exciting, but it raises the stakes for your hero because you almost feel that they cannot escape.

Movement of objects

Of course, exaggerating the rapid approach of a person isn’t the only application. It works with pretty much anything including cars.

Having something like a car approaching the audience at rapid speeds adds intensity to your scene.

Facial features

Since long and wide lenses compress or exaggerate the perception of how close an object is to frame, this also affects how faces look in the frame.

For example, facial features will be evened out in proportion, or ‘flattened’, by longer lenses. On the other hand, wider lenses tend to exaggerate facial features, or at least whatever is closest to the lens at the time.

Of course, if your subject is pretty far from the camera, this effect won’t be very noticeable, if at all, but if the subject is close, it will have a significant impact on your image.

2.5 CHANGE PERSPECTIVE

Move the Camera

When you add camera movement, things get more complicated, as you are then changing the perspective of the audience by physically changing proximity to objects, subjects, and your background.

You may be excited to film a big tracking shot in your next project, which means you’ll be moving the camera with your subject.

Think about how you want the viewer to feel, and then make focal length, camera stability, movement speed, and production design to generate that intended feeling. The more thoughtful, the better the result.

Depending on what lens you are using, your image will then change according to the effect that focal length creates.

That is why it’s so important to learn the different effects that focal length has on your image, and ultimately, your audience.

When you know how to use the tools available to you, you can twist them to your purposes, such as for comedic effect.

A unique technique that uses the power of focal length and camera movement is the the famous "vertigo" effect popularized by filmmakers such as Alfred Hitchcock and later Stephen Spielberg.

The reason this effect is possible is because it is using the relationship between how the lens compresses the image and the physical movement of the camera in unison to warp the visual perspective.

Another use is the iconic ‘Bayhem’ shot, which adds drama to a shot.

It creates parallax movement and depth by having the subject move opposite the direction the camera is moving, with a long lens, which exaggerates the movement.

The background appears to whip past the actor due to image compression.

Your camera and lens are the audience. Your audience sees no more and no less than what you show them. It is crucial that when telling your story, you consider all the aspects of visual storytelling for your film.

All the small creative storytelling choices that you make for each image of your film are important. These small choices coalesce into the powerful effects your audience will feel as your story unfolds before them.