Basic Cinematography

What is Focal Length in Cinematography?

In this video I explain the useful features of focal length in cinematography and how to exploit it for maximum impact.

Written by Sareesh Sudhakaran and Lamia Sabic

Forget the technical definition of focal length, it’s unnecessary to understand it or practice cinematography.

In this video I explain only the useful features of focal length in cinematography and mainly how to exploit focal lengths for maximum impact:

The Angle of View

Lenses cut out parts of what’s in front of you, and only show a portion of it. You can actually measure the angle of it from the position of the camera, and you have what is called the angle of view.

Want to get a tighter shot? There are two ways. You can either walk closer, or you can get a different lens with a smaller angle of view.

It’s important to pick the right camera, depending on where and what you’re shooting. When it comes to sensor sizes, there are full-frame and crop sensors.

A full-frame sensor will give you a wider angle of view for the same lens, while a crop sensor will give you a tighter angle of view.

Full-frame vs Crop Cameras

Full-frame cameras have a sensor which is in the same dimensions as a 35mm film format. This is consider to be a standard, due to its long usage as a uniform format for production from the early 20th century. The focal lengths of lenses are based on this 35mm standard.

But, if you’re using a camera with a crop sensor, the focal length of the lens will not determine your angle of view. What a crop camera does is what its name implies – it crops out a part of the image from what you would usually see on a full-frame camera. A crop sensor is any kind of sensor which is smaller than the 35mm standard. The common types of crop sensors are the APS-C and micro 4/3 systems.

In order to know the angle of view or focal length with a crop sensor, you can measure it by the focal length multiplier.

Crop Factor

Crop factor on camera sensors changes depending on the manufacturer of the camera. For example, the crop factor of a Canon APS-C camera is 1.6x.

What does that mean?

The image will look different if you’re using a 50mm lens on a Canon 5D, a full-frame sensor camera, or on a Canon 70D, an APS-C crop sensor camera. On the Canon 5D, you will get an image you expect from a 50mm lens. But, with a Canon 70D the focal length of the lens is multiplied with the crop factor (50×1.6), resulting in a focal length or angle of view of 80mm. If you would put a 35mm lens on the Canon 70D, you would roughly get a look of a 50mm on a full-frame camera.

The quality of your image is directly influenced by the quality of your sensor.

There has been a long and bloody debate about sensor sizes and the advantages of full-frame over crop sensor cameras. Full-frame cameras do over-perform in two things, which are more limiting on crop sensor cameras – they are better in low-light settings and they will get you a shallower depth of field. Apart from that, you could say that it doesn’t matter if you have a full-frame or a crop sensor camera – as long as you know what you’re doing and what you want from your image.

The Focal Length

The number we give lenses to represent the angle of view, is the focal length. It does have a technical definition as well, but that definition is in no way useful to cinematographers. If you want to know what it is, wikipedia is a good place. For those who don’t want to waste time on unnecessary theory, all you have to know is the angle of view is always, always dependent on the size of the sensor.

A larger sensor will give you a wider angle of view for the same lens, while a smaller sensor will give you a tighter angle of view.

Since sensor sizes are all over the place nowadays, if you put the same lens on different cameras, you might get different angles of view. A Sony a7S II will be different from the Panasonic GH5 will be different from a Red Raven will be different from an Arri Alexa, becaue their sensor lengths are all different.

So what we really need is a gold standard. Some starting point from which to calculate the rest if we ever need to. I’ve written an extensive article on the 35mm equivalent and crop factors if you want to learn more, I’ve decided the 35mm full frame format is the best gold standard we have today. It’s been around long enough and is most relevant for cinematography. By 35mm full frame I’m talking about 135 or a sensor measuring exactly 36mm x 24mm. The Nikon D4, D850, Sony a7S II, a7R III and so on are all full frame sensors.

Wide Angle, Normal and Telephoto

We can also differentiate between the types of lenses based on the different focal lengths they provide. Depending on this, all of them can be used to shape the image and enhance the narrative of the film.

Ultra wide-angle lens – focal length between 8mm and 24mm

These are extremely wide lenses, allowing you to capture almost 180 degrees around the lens. In film, one of the notorious uses of an 18mm lens was in the noir film Touch of Evil, by Orson Welles. Since this focal length wasn’t frequently used by directors at that time, Orson Welles said he found a freshness within that look of the image. 

If the focal length is up to 14mm these lenses are called fisheye lenses. Due to their wide viewing area, they create visible distortions in the image. For that reason, fisheye lenses are almost never used in film.

Wide-angle lens – focal length between 24mm and 35mm

Wide angle lenses have a small focal length and a wide angle of view. In film, they are great for master shots, as they include all of the information of a wider space with very little distortion. If you use a wide-angle lens, you can also approach a subject without excluding the background information. But, careful not to approach too close the subject with a wide-angle lens, as you will create distortions in the image.

Roger Deakins, known for his cinematography work on films of the Coen brothers, considers 27mm to be his preferred option for a wide angle shot.

Standard/normal lens – focal length between 35mm and 70mm

A standard/normal lens produces an image which roughly matches what we see with our eyes. The best equivalent of this is the 50mm lens, which is one of the most versatile and used lenses. They create almost no distortions, making them perfect for portraits of subjects.

The Japanese master Yasujiro Ozu used only a 50mm lens for his entire films. As this look is considered to resemble the focal length of the human eye, Ozu used it to create a naturalistic approach to his story. Another more recent example of single-lens use in a film is Call Me By Your Name, directed by Luca Guadagnino. Luca Guadagnino with his director of photography Sayombhu Mukdeeprom took on the challenge of filming the entire film with a 35mm lens. Their aim was to maintain the sense of the human eye, while still allowing the space to breathe.

Telephoto lens – focal length between 70mm and 300mm (or more)

Telephoto lenses can be characterized as lenses which have a focal length bigger than the physical size of the lens. They are sometimes mistaken for zoom-lenses, even though they don’t necessarily need to be a zoom lens. They come in a range of focal lengths, from medium-telephoto (from 67mm to 206mm) and super-telephoto (over 300mm). They are great for isolating your subject from the background, but should be handled on a tripod due to their size. It becomes hard to track a subject with these lenses, since the slightest shake of the lens is visible in the image. But, if you can make your movement smooth and not too fast, zoom lenses can also become a valuable tool.

So let’s say I want a wide angle of view. To get that I use what is very loosely called a wide angle lens. Let’s just say we’re using a 24mm lens for this example. What’s this “24mm”? It’s just a name. It’s not 24 degrees, but it represents a certain angle of view on a 35mm full frame sensor, and we call it wide angle, through tradition.

Focal lengths are written as XXmm, where XX is a number (single digit to as high as four digits)

Any number smaller than this is wider. So the wider you need to go, the smaller this number gets. It’s always in millimeters and is written on the front and sides of your lenses. This number is called the focal length.

The higher the number, the smaller the angle of view. Of course, this is only true if you’re using the same sensor for comparison. E.g., a 24mm lens on a full frame camera is wide, but the same lens on a Micro Four Thirds sensor would be the equivalent to a 48mm lens. If this is confusing to you, then please read my article on the crop factor and the 35mm equivalent. Now here’s the thing, a 48mm is not considered wide. In fact, in the full frame world, a 50mm lens is considered normal, by tradition.

So we have a range of lenses that go from super wide to wide angle. Through tradition, wides roughly end at about 35mm. From 35mm to about 70mm we have the normal range. And finally, anything above 70mm could be considered telephoto. When it goes beyond 200mm, people also call it super-telephoto. Beyond 2000mm, you’re looking at a telescope.

If you want to shoot a wide vista, say the grand canyon, you might love the ultra wide angle focal lengths. If you want to shoot mid shots or documentary-style, you might like the normal range, if you want to flatter your star, then pick a telephoto lens.

The Emotional Aspect

The angle of view of a lens is just one function of the focal length. Different focal lengths have different emotional impacts. If you shoot a closeup of a person with a 24mm, the emotional response will be totally different when compared to a 50mm, and that will be different to a 135mm. The more telephoto you go, the more the background comes closer. Wide angles make things appear more spacious than it actually is. Are you in a small room? Then use a wide angle lens to make it look bigger. YouTubers do this all the time to make their rooms look bigger.

When you use a wide angle lens, the faces tend to distort outwards, making them rounder. The nose looks bigger and more pronounced. Some cinematographers love the wide angle look. The most famous of them today being Emmanuel Lubezki. Check out my video on his cinematography:

Some cinematographers prefer the normal range, Roger Deakins is a great example. He loves a 32mm lens on the Super 35mm format, which would roughly be a 45mm lens on a full frame 35mm sensor. Watch my video on his cinematography:

A good example of consistent telephoto use would be Ridley Scott’s films, and many TV shows running today. They make the stars look good, so why not?

The Takeaway – the important things you need to know about focal lengths

So what do you really need to know about focal lengths when you’re a beginner? Just three things:

  1. Focal lengths by itself don’t really mean anything. You also need to know the size of the sensor it’s going to be used for.
  2. The smaller the number the wider it gets and more spacious everything looks. The larger the number the tighter it gets and more compressed or restricted everything looks.
  3. Most important. Different focal lengths tell a story differently. The entire emotional impact changes for the same sized shot with different focal lenses, so choosing the right focal length is hugely a matter of personal taste. Movies like Amelie have used super wides but still have faces look great, because the director knew when to stop. There’s a lot of personal aesthetics involved here.

How do you know which one you should pick?

Here’s a simple trick. Have you clicked photos? Go back to all the photos you have clicked, and see if you’ve cropped them mostly. If you’ve cropped most of your photos then you probably are not a wide-angle person. On the other hand, do you feel most motivated with a wide angle lens? Then maybe that’s the focal length range you should start out with.

The traditional range runs like this:

  1. 14mm is ultra wide.
  2. 24mm is wide.
  3. 35mm is between normal and wide, and many consider this to be close to what the eye sees.
  4. 50mm is normal, which means the face is not distorted, and it gives you the most unbiased look, if you will.
  5. 85mm is portrait, and flatters your subject. Telephoto distorts the other way, makes faces look thinner. Anything more will flatter them even more, but you are hit with the practical limits of space in cinematography. You have to move further back but there might not be room.
  6. If you need to shoot wildlife or birds, then go telephoto or even super-telephoto.

Primes or Zooms?

If you know exactly what you want, then you can work with prime lenses.

Prime lenses are lenses with just one focal length. If you know you like a range, say normal range, then pick a zoom lens in that range. That’s why you see most camera companies have three main zooms – 16-35mm, which is the wide range, 24-70mm, the normal range, and 70-200mm, the telephoto range. See? Other people have already done the thinking for you.

Prime lenses are preferred by cinematographers because of the image quality they produce and the speed of the lens. Since they have fewer glass elements within their construction, the light is less distorted once it reaches the sensor. This results in a clearer and sharper image.

The speed of the lens is determined by the aperture (f/stop); with a lower f/stop you can shoot in lower light setting and use a faster shutter speed. For example, prime lenses with a f/1,8 or f/1,4 are highly desired.

Zoom lenses have a different range of focal lengths, due to their more complex construction. The focal length on zoom lenses can be changed by turning the zoom ring on the lens. For that reason zoom lenses are usually more difficult to produce and they are consequently more expensive than prime lenses.

If you know you like a range, say normal range, then pick a zoom lens in that range. That’s why you see most camera companies have three main zooms – 16-35mm, which is the wide range, 24-70mm, the normal range, and 70-200mm, the telephoto range. See? Other people have already done the thinking for you.

Zoom lenses can be a great asset if you’re on a tight shooting schedule and you cannot afford to waste time changing lenses. You can just change your focal length on the zoom ring, within the range of your lens. Also, zoom lenses are usually not as fast as prime lenses. If you’re thinking of buying a quality, fast zoom lens, be prepared to invest more money.

Focal Length and Film Directors

One amongst many decisions which directors have to continuously make during the shooting is the focal length of each shot. In most cases, this is a mutual decision between the director and the cinematographer.

Focal length directly establishes two crucial points: what is in the frame of the image and the depth of the image (or the 3-dimensional space of the image).

Directors use focus length and lenses to create a personal style – a fingerprint of their filmmaking language. We already mentioned some in this article, but if you’re interested in watching what famous directors prefer as their focal lengths, you’ll love this video:

Director’s Viewfinder

We all have an image in our head of a film director holding his hands up, trying to establish the framing of the image with his fingers. This is an old technique and it’s rarely used today.

Instead, you can sometimes see a director walking around with a little gadget hanging around the neck. This is called the director’s viewfinder. It’s used by directors or cinematographers to determine the framing of the image, or in other words – the focal length needed for the shot.

Everybody uses a viewfinder in their own way. For some it’s helpful during the shooting, while others prefer it during the pre-production phase, when they’re location scouting and planning the shoot.

Either way, if your budget allows it, the director’s viewfinder can be a helpful tool. In recent years, a more affordable option appeared – software-based viewfinders. They are available on smartphones and are considerably cheaper than a traditional director’s viewfinder.

Some directors prefer to rely on their directors of photography, leaving the camera-related decisions to them. Needless to say, the trust between a director and DP is crucial.

But as we learned from previously mentioned examples; it’s equally important for a director to understand how focal length and lens choice, along with other important choices, build the character of the film.

The right question to ask about focal lengths is:

How do you see the world? I bet a focal length already exists that will make that come true.

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