Focal Length Explained: What 24mm, 50mm and 85mm Really Do to a Photo

The number on your lens decides how much of the scene fits in the frame. Where you stand decides how faces and backgrounds look. Here is the camera lens focal length range from 18mm to 200mm, on one scene and one portrait.

• Lengths compared18mm to 200mm
• FormatFull frame
• Portraits shot byPHLEARN, 2012

Put a wide zoom on, walk up close to someone’s face and take a picture. Then step all the way back, zoom to 200mm and take the same head-and-shoulders frame. The two photos look like two different people. The nose, the ears, the width of the face, the size of the wall behind them: all of it changes, and you didn’t touch a slider.

That’s what the millimetres on a lens are about.

This guide gives you camera lens focal length explained with real pictures: one scene from one spot at seven focal lengths, and one portrait shot from 21mm to 200mm in our studio. By the end you’ll know what focal length means, what it changes and what it doesn’t, and which length to reach for when. Everything here assumes a full-frame camera, where the numbers on the lens mean what they say; smaller sensors get their own section near the end.

What Does Focal Length Mean?

Camera lens focal length is a distance, measured in millimetres, from the lens’s optical centre to the sensor when the lens is focused at infinity. It isn’t the physical length of the lens. A 50mm lens can be shorter than your hand, and most long lenses are built so the barrel is shorter than the number on it.

In practice, a shorter focal length sees a wider angle, so more of the scene fits in the frame and everything in it looks smaller. A longer focal length sees a narrower angle: less fits in, and what’s left is magnified. On a zoom, the two numbers are the ends of its range, so a 24-70mm can be set anywhere from 24mm to 70mm. A prime has one focal length, and you zoom with your feet.

People sort the range into rough groups, and the borders are loose. Nikon’s focal length guide, for example, calls 14–35mm wide, 50–60mm standard and 70–200mm telephoto on full frame. This is the split we use in this guide:

The angles are worked out from the full-frame sensor’s diagonal (about 43mm), and they change on other formats.

The Same Scene From the Same Spot

The quickest way to see what focal length does is to keep everything else still. Here is one photo of the Römerberg square in Frankfurt, taken at 18mm on a full-frame Sony, with white frames showing what each longer focal length would have caught without the photographer moving an inch.

24mm

35mm

50mm

85mm

135mm

200mm

Find the 200mm frame inside the 18mm photo and you have the same picture. From one spot, a longer lens is a crop: it adds magnification and nothing else. The 200mm version is far sharper than an enlarged crop would be, because the whole sensor is spent on that small rectangle, but the shapes and the overlap of the column and the houses are identical.

That’s the most useful thing to understand about focal length, and it clears up most of the confusing advice about it. Focal length sets the frame. Your position sets the perspective.

The Same Portrait From 21mm to 200mm

In 2012 we photographed Broderick in our Chicago studio with three lenses on a full-frame Canon 5D Mark II: a 16-35mm, a 50mm and a 70-200mm. The light stayed where it was, and for each focal length the camera moved so that he filled about the same part of the frame. The focal lengths and distances below come from the files themselves (the distance is the focus distance the lens recorded, so treat it as approximate).

21mm · about 0.6 m

25mm · about 0.9 m

35mm · about 0.7 m

50mm

70mm · about 1.8 m

100mm · about 2.5 m

135mm · about 3.5 m

200mm · about 5 m

Three things change as the numbers go up, and none of them is the lens itself.

His face. At 21mm his nose and the middle of his face are noticeably closer to the camera than his ears, so they come out bigger, and the ears fall away behind the cheeks. At 200mm, five metres back, the tip of his nose and his ears are almost the same distance away, so they come out at their real sizes. The face looks wider and flatter, which most people read as calmer and more flattering.

The background. At 21mm you can see the ceiling, the fluorescent tubes and a corner of the softbox. At 200mm all you see is a patch of the dark backdrop right behind him. The room didn’t change. The narrow angle simply takes in a much smaller piece of it.

How it feels. The 21mm frame feels close and a little confrontational, as if you’re standing in his space. The 200mm frame feels like looking at a portrait. Neither is wrong. When we shot the series, the point was that a wide lens up close is a special effect, and the longer lengths are what to use when you just want someone to look like themselves.

Compression and Distortion: What’s Really Happening

Two words come up in every conversation about focal length, and both are usually explained backwards.

Compression is the look of a long lens: the background seems huge and close, and layers of a scene stack up on each other. It comes from distance. When you stand far back, the gap between your subject and the background is small compared with the gap between you and your subject, so the two appear at similar sizes. A long lens doesn’t cause that; it just lets you fill the frame from that far back. Stand in the same place with a wide lens and crop, and you get the same compression with fewer pixels, exactly as the Frankfurt crops show.

Distortion means two different things, and it helps to keep them apart:

• Perspective distortion is the big nose at 21mm. It comes from being close. A wide lens doesn’t distort a face from five metres away; it just makes the face tiny. You can’t truly undo it in software, because nothing is wrong with the image. The camera really was that close.
• Lens distortion is the lens bending straight lines: barrel distortion bows them outwards, common on wide zooms, and pincushion pinches them inwards, common on telephoto zooms. A lens profile fixes most of it. In Lightroom Classic it’s Enable Profile Corrections in the Lens Corrections panel; in Camera Raw it’s Use profile corrections in the Optics panel.

There’s a third effect at the wide end. Near the edges of a wide-angle frame, round things stretch, so a face in the corner of a 16mm frame looks pulled sideways even from a sensible distance. Keep faces towards the middle and they look a lot more normal. Tilting a wide lens up at a building has a similar side effect, because the verticals lean in. Keep the camera level if you can, and straighten what’s left with the perspective tools in Lightroom.

What Each Focal Length Is For

These are starting points. Plenty of great portraits are taken at 24mm and plenty of great landscapes at 200mm; what changes is how the photo feels.

16mm: Room for Everything

At 16mm the frame takes in about 107° across the diagonal, more than you can take in without moving your eyes. It’s the length for interiors, small rooms, big skies, night skies and landscapes where a rock or a flower right in front of the lens leads into the distance. One of Aaron’s favorite images, “The Flood”, was shot at 16mm for exactly that reason: it was made in a very small room in an abandoned barn, and the wide lens is what gets both the floor and the ceiling in.

24mm: Wide but Still Natural

24mm (84°) is wide enough to show where you are, but straight lines and people stay believable if you’re careful. It’s a great travel and landscape length, it handles groups in tight spaces, and it makes environmental portraits where the place matters as much as the person. It’s also close to what a phone sees: Apple lists the iPhone 17 Pro’s main camera as 24mm, in full-frame terms.

35mm: The Storyteller

At 35mm (63°) you see a person and their surroundings at once without the wide-angle look. It’s the classic length for street, documentary and wedding photography, because you can work close to people and the photo still feels like being there.

50mm: The Standard

A 50mm on full frame (47°) gives a view that looks natural to most people. Strictly, the “normal” lens for full frame is about 43mm, the length of the sensor’s diagonal, but 50mm became the standard lens of 35mm film cameras and the name stuck. A 50mm f/1.8 is still one of the best first prime lenses you can buy: small, inexpensive, and it lets in a lot of light. Use it for half-body portraits, everyday photography, food and low light.

85mm: The Portrait Length

85mm (29°) is the length most photographers associate with portraits, and the series above shows why. For a waist-up frame like ours you stand roughly two metres back, close enough to talk easily, far enough that the face keeps its real proportions. Head-and-shoulders portraits and headshots usually sit anywhere from 70mm to 100mm; in our corporate headshot tutorial we shot at around 80mm.

135mm: Tight Faces, Simple Backgrounds

At 135mm (18°) you’re three to four metres from someone for a waist-up portrait, and the background behind them is a small, blurred patch. It’s great for tight portraits, candid moments at events where you don’t want to be in anyone’s face, stage work, and picking out a detail in a landscape.

200mm: Pull It Close

200mm (12°) brings far things close and stacks layers together: hills behind hills, a subject in front of a big setting sun. It’s the long end of the classic 70-200mm zoom, the workhorse for sports, events, outdoor portraits with a clean background, and landscapes where you want to show one small part of a scene. It also cures leaning buildings: step back far enough and you can photograph a facade straight on with the camera level. Beyond 200mm you’re in super-telephoto territory, 300mm to 800mm, where wildlife and field sports live.

Focal Length on a Smaller Sensor

The camera lens focal length printed on the barrel never changes: a 50mm lens is always 50mm. Put it on an APS-C camera, though, and the smaller sensor only records the middle of the picture, so it frames like a longer lens would on full frame: about 75mm on Nikon, Sony and Fujifilm APS-C, and about 80mm on Canon. That’s the crop factor, and it changes which lens does which job. The full explanation, with the same scene on both sensor sizes, is in our guide to full frame vs APS-C and crop factor.

How Focal Length Affects Background Blur

Longer lenses seem to blur backgrounds more, and in practice they do, if only indirectly: to keep the same framing you stand farther back, and the narrow angle takes in a small piece of the background and magnifies it, blur and all. That’s why our 135mm frame has a smoother, simpler background than the 35mm one. Aperture still does most of the work. For more on that side, read Understanding Aperture and our bokeh photography guide. If the blur didn’t happen in camera, the Lens Blur tool in Lightroom Classic can add it afterwards.

Common Focal Length Mistakes

Most focal length mistakes come from treating the zoom ring as a way to move.

Zooming instead of moving. The ring only changes the frame. If a portrait looks unflattering, the fix is usually to step back and zoom in, not to zoom out and get closer. Kit zooms are where this happens most, because a lot of beginners leave them at the wide end: at 18–24mm on a crop camera, or 24mm on full frame, a close head-and-shoulders frame will enlarge the nose.

Mixing focal lengths in a composite. If you photograph a person at 200mm and drop them into a background shot at 16mm, the perspective won’t match, however good the masking is. Shoot the pieces from similar distances and heights with similar focal lengths, and the composite has a much better chance of looking real.

Common Questions About Focal Length

Does a higher focal length mean more zoom? Yes. A higher focal length magnifies more and takes in a narrower angle. A 200mm lens shows things four times as large as a 50mm lens does from the same spot.

Does focal length change perspective? No. Perspective comes from where the camera is. Focal length only decides how much of that view you frame.

What is the best camera lens focal length for portraits? For head-and-shoulders portraits that look like the person, most photographers use 70mm to 135mm on full frame, with 85mm the classic choice. Wider lengths work for environmental portraits, as long as you’re not too close to the face.

Is 50mm the same as the human eye? Not exactly. Your eyes take in a far wider area than any 50mm frame, but a 50mm photo looks natural to most people, which is why it’s called a standard lens.

What does 18-55mm mean on a lens? It’s a zoom that goes from 18mm to 55mm. That range is usually made for APS-C cameras, where it frames like roughly 27–83mm would on full frame (29–88mm on Canon).

Spend a Day at One Focal Length

To feel it for yourself, spend a day with one focal length. Tape the zoom ring if you have to. By the end of the day you’ll start seeing frames at that length before you lift the camera.