Parts of a Camera: A Visual Guide to Camera Anatomy

A camera is a light-tight box with a lens on the front and a sensor on the back, plus the parts that control how much light gets through, for how long, and what happens to the picture afterwards. Knowing what each part does turns the buttons from a puzzle into a set of decisions, and lets you read your own photos: the sun star above was made by the aperture blades inside the lens.

This page names every part, then follows the light through the camera in order, shows the mark each part leaves on a photo, and tours the body from front to base. The same parts, in some form, are inside every camera you are likely to hold, from a phone to a DSLR.

Camera parts and what they do

• Lens: Where it is: Front, attached to the mount. What it does: Gathers light and focuses it into a sharp image on the sensor. Sets the focal length and the widest aperture available.
• Lens mount: Where it is: Front of the body, the metal ring around the opening. What it does: Locks the lens to the body at an exact distance from the sensor and, on most systems, passes power and data between them. A release button beside it unlocks the lens.
• Focus ring: Where it is: Lens barrel. What it does: Sets focus by hand. On many lenses it also fine-tunes what autofocus chose. See manual focus.
• Zoom ring: Where it is: Lens barrel, on zoom lenses only. What it does: Changes the focal length, so the view gets wider or tighter.
• Aperture (diaphragm): Where it is: Inside the lens. What it does: An adjustable opening made of overlapping blades. It controls how much light passes and how deep the zone of sharpness is. See aperture.
• Lens hood: Where it is: Front end of the lens. What it does: Shades the front glass from light outside the frame, which cuts flare and haze. See lens hood.
• Shutter button: Where it is: Top of the grip, under your index finger. What it does: Half press to focus and meter, full press to take the picture.
• Mode dial: Where it is: Top of the body. What it does: Chooses who sets the exposure: you, the camera or a mix. See camera modes.
• Command dials: Where it is: Top and back, under thumb and index finger. What it does: Change the setting the current mode needs, such as shutter speed, aperture or exposure compensation.
• Hot shoe: Where it is: Top centre of the body. What it does: A mount with electrical contacts for a flash, trigger or microphone. See hot shoe.
• Viewfinder: Where it is: Back, at the top, in the centre or at the left corner, with a rubber eyecup. What it does: Lets you compose with the camera at your eye. Optical in a DSLR, a tiny screen in a mirrorless camera.
• Diopter adjustment: Where it is: Beside the eyepiece, a small wheel or slider. What it does: Matches the viewfinder to your eyesight. It changes how sharp the view looks to you, not the picture.
• Rear screen: Where it is: Back of the body. What it does: Shows live view, menus and playback, including a histogram of the shot.
• AF point selector: Where it is: Back, under your thumb (a joystick, pad or touch screen). What it does: Moves the autofocus point to your subject.
• AF-ON and AE-L buttons: Where it is: Back, near the thumb rest (labels vary). What it does: Start autofocus without the shutter button, and lock exposure. See back button focus and AE lock.
• Menu and playback buttons: Where it is: Back, beside the screen. What it does: Open the settings and review saved pictures. See camera menus.
• Shutter: Where it is: Inside, just in front of the sensor (or inside the lens, in a leaf shutter). What it does: Decides how long light reaches the sensor. See mechanical shutter.
• Sensor: Where it is: Inside, at the back of the chamber, facing the mount. What it does: Turns light into an electrical signal, one photosite per pixel. See how image sensors work.
• Mirror (DSLR only): Where it is: Inside, behind the mount, angled at 45 degrees. What it does: Sends the lens image up to the optical viewfinder, then flips out of the way for the exposure.
• Pentaprism or pentamirror (DSLR only): Where it is: Inside the hump above the mount. What it does: Turns the image from the mirror upright and the right way round for your eye.
• Image processor: Where it is: Inside the body. What it does: Turns the sensor’s signal into a picture file, runs autofocus calculations and drives the screens.
• Buffer: Where it is: Inside the body, beside the processor. What it does: Fast memory that holds pictures until the card can take them. When it fills, a burst slows down. See buffer.
• Image stabilization: Where it is: Inside the lens, the body or both, on cameras that have it. What it does: Moves a lens element or the sensor to cancel small hand movements. See image stabilization.
• Memory card slot: Where it is: Side of the body, or in the base beside the battery. What it does: Holds the removable card the pictures are saved to. See memory cards.
• Battery compartment: Where it is: Base of the body or inside the grip. What it does: Holds the rechargeable battery.
• Tripod socket: Where it is: Underside, usually in line with the lens. What it does: A threaded hole for a tripod or plate. See how to use a tripod.
• Ports: Where it is: Side of the body, under a flap. What it does: Connect the camera to a computer, charger, monitor, microphone or headphones.

Follow the light: how the parts work together

The table tells you where things are. To understand the machine, follow one ray of light from the scene to the memory card. Each part exists because of a problem the part before it left behind.

A bare sensor in open air records no picture at all, because light from every point of the scene lands everywhere at once. Put the sensor in a dark box with a tiny hole, and each point of the scene lands in one place: you get an image. That is a pinhole camera, and it works, but a hole small enough to be sharp lets in so little light that exposures run to seconds or minutes. A lens solves that. It gathers light through a much wider opening and bends it back to a sharp point. Now there is too much light in bright scenes and too little depth of sharpness, so the lens gets an adjustable aperture. Finally, the shutter decides when the light starts and stops.

In order, the path through an interchangeable-lens camera is:

1. Lens elements. Several groups of glass bend the light to a focus and correct each other’s flaws, such as chromatic aberration. The image they form is upside down and reversed left to right.
2. Aperture. The blades inside the lens set the size of the opening the light passes through.
3. Mirror (DSLR only). While you compose, it reflects the image up to the focusing screen, the pentaprism and the eyepiece, which turn it upright for your eye. At the moment of exposure it swings up out of the way.
4. Shutter. Two curtains just in front of the sensor open and close to set the exposure time.
5. Filter stack. A thin pack of glass on the sensor blocks infrared light and, on many cameras, softens the image very slightly to prevent moire patterns.
6. Colour filter and sensor. Each photosite sits under a red, green or blue filter, usually in a Bayer pattern of half green, a quarter red and a quarter blue. A photosite measures only how much light arrived, never its colour.
7. Processor. The sensor’s signal is amplified and turned into numbers, then the processor works out full colour for every pixel from its neighbours (demosaicing), and either builds a JPEG or keeps the raw data. See RAW vs JPEG.
8. Buffer, then card. The finished data waits in the buffer until the memory card has written it.

A mirrorless camera follows the same path without step 3: the sensor sees the scene all the time and the processor shows it on the screens. A phone does the same, with a tiny fixed lens and an electronic shutter.

Want to know what happens on the sensor itself, from photon to number? How image sensors work goes through photosites, colour filters and the readout.

Every part leaves a mark in your photos

You can see most of these parts in a finished picture if you know where to look. That is the fastest way to understand them: each part you can touch controls a result you can see.

• Aperture blades: What you see in the photo: Sun stars around bright points at small apertures, the shape of out-of-focus highlights (bokeh), and how much of the scene is sharp. What controls it: The f-number.
• Shutter: What you see in the photo: Moving things frozen sharp or drawn into streaks. What controls it: Shutter speed.
• Sensor and processor: What you see in the photo: Grain-like noise in dark areas, how much detail survives in bright skies and deep shadows. What controls it: ISO, exposure, and sensor size.
• Lens elements: What you see in the photo: Sharpness at the edges, coloured fringes on high-contrast edges, straight lines bending near the frame edge. What controls it: The lens itself, the aperture, and lens corrections.
• Lens hood: What you see in the photo: Flare and haze that are not there when the hood is on. What controls it: Whether you use it.
• Image stabilization and tripod socket: What you see in the photo: Static subjects sharp at slow shutter speeds. What controls it: Whether stabilization is on, or the camera is on a tripod.
• Dust on the sensor: What you see in the photo: Soft dark spots in the same place on every frame, most visible in skies at small apertures. What controls it: Cleaning the sensor.

The sun star in the opening photo is the aperture at work. At f/16 the blades close to a small polygon, and light bending around their straight edges spreads into rays. A lens with an even number of blades gives that many points; an odd number gives twice as many, because each pair of opposite edges makes its own rays.

The aperture leaves a second mark: how much of the scene is sharp. Pick the photo below with the shallower depth of field, then read why.

Which photo has a shallower depth of field?

A B

The fireworks above are the shutter at work. At 1/6 s, each spark kept moving while the curtains were open, so the sensor recorded its path as a line. At 1/1000 s the same sparks would be dots. The Camera Simulator lets you change shutter speed and aperture on a virtual camera and see the result before you try it on a real one.

Now read the shutter’s mark yourself: pick the photo below that used the faster shutter speed, then read why.

Which photo used a faster shutter speed?

A B

The night sky above needed three parts working at their limits at once: the aperture wide open at f/1.8, the shutter open for 15 seconds, and the sensor’s signal amplified at ISO 3200. None of them could do it alone, and how they trade against each other is the exposure triangle. For those 15 seconds the camera also had to stay perfectly still, which is the job of the tripod socket in the base.

Front of the camera: lens, aperture and mount

The front is where light comes in. The lens bends it into an image, the mount holds the lens in place, and a release button beside the mount lets you twist the lens off.

The aperture is in the lens, not the body. Its size is given as an f-number, which is the focal length divided by the diameter of the opening. A 50 mm lens at f/2 has an opening 25 mm across; at f/4 it is 12.5 mm. Halving the diameter quarters the area, so f/4 lets in a quarter of the light of f/2, two stops less. The same arithmetic says f/16 lets in about 1/32 of the light of f/2.8, five stops less, because (16 ÷ 2.8) squared is about 32.7.

The two rings on the barrel are the focus ring and, on a zoom lens, the zoom ring. Many lenses also carry switches for autofocus and stabilization, and a bayonet at the front for the hood.

The mount does more than hold the lens on. It fixes the distance from the mount to the sensor, called the flange distance, and every lens for that mount is designed around it. DSLR mounts sit roughly 44 to 47 mm in front of the sensor, because the mirror needs room to swing. Mirrorless mounts sit roughly 16 to 20 mm away. That is why adapters work in one direction only: a lens made for a long flange distance can sit on a short-flange body with an adapter that fills the gap, but a mirrorless lens cannot be pushed far enough back into a DSLR to focus at infinity.

Have an old lens you would like to use on a new body? Adapting vintage lenses covers which combinations work and what you give up.

Top of the camera: the controls you use while shooting

The top holds the controls you reach for most, and the layout has barely changed since film. The shutter button sits on the grip, the mode dial or its equivalent on a shoulder, and the command dials where your thumb and index finger fall naturally. On most bodies the hot shoe sits on top, directly above the lens, so a flash or microphone points the way the lens does.

The shutter button has two stages. A half press starts autofocus and takes a meter reading. A full press takes the picture. Stabbing it in one go moves the camera and can fire before focus has locked, so press halfway, wait for the focus confirmation, then squeeze. If a full press does nothing, the camera won’t take a picture page lists the usual causes.

The mode dial decides who sets the exposure, and nothing else. In aperture priority you set the aperture and the camera picks the shutter speed. In shutter priority it is the other way round. In manual you set both. Across these modes the picture looks no different for the mode you used; only the settings matter. The command dials then change whatever the mode leaves to you.

Want to set the aperture yourself and let the camera handle the shutter speed? Aperture priority mode covers how it works and when to use it.

Back of the camera: viewfinder, screen and buttons

The back is where you look and where you review. The viewfinder is a small window at the top with an eyecup that blocks side light. The rear screen takes up most of the rest. Some screens are fixed, some tilt, and some swing out and rotate, which helps with low and overhead angles.

If the viewfinder looks soft even when focus is right, turn the diopter until the numbers and lines inside it look crisp. It is set to your eye, not to the lens, and it changes nothing in the picture. See viewfinder and screen basics.

The buttons around the screen vary between cameras, but the jobs are common: picking the autofocus point, starting autofocus separately from the shutter button, locking exposure, opening the menus and playing back pictures. Most are shortcuts to menu settings, and many can be reassigned, so the label tells you the default job, not the only one. More buttons mean faster access, not more ability.

Inside the camera: shutter, sensor, processor and buffer

The shutter

In most interchangeable-lens cameras the shutter is a focal-plane shutter: two curtains just in front of the sensor. The first curtain opens, the second follows it and closes, and the delay between them is the exposure time. At fast speeds the second curtain starts closing before the first has finished opening, so a narrow slit travels across the sensor. That is why flash has a top speed, the flash sync speed, often around 1/200 s. Above it, a flash burst would light only the band of sensor that the slit happens to uncover.

A leaf shutter works differently. It sits inside the lens, made of blades like an aperture, and opens from the centre outwards. It syncs with flash at any of its speeds and is common in fixed-lens compact cameras and some medium format lenses.

Most mirrorless cameras keep the mechanical shutter open while you compose, because the sensor has to feed the screen. When you press the button, the shutter closes, opens to start the exposure, closes to end it, and opens again for live view. That is why some mirrorless cameras sound like two quick clicks. Many use an electronic first curtain instead: the sensor starts the exposure electronically and the mechanical curtain only ends it.

An electronic shutter has no moving parts. It starts and ends the exposure electronically, row by row, and on most sensors it reads the rows out one after another, top to bottom. A subject that moves during that readout lands in a slightly different place on each row, so propellers bend and fast pans lean. That is rolling shutter. A global shutter reads every row at once and avoids it.

Which shutter should you actually use? Mechanical vs electronic shutter compares the shutter modes in your menu and what each does to the picture.

The sensor

The sensor is a grid of photosites, each collecting light during the exposure. The count gives the megapixel figure: a sensor 6,000 photosites wide and 4,000 tall has 24 million, or 24 megapixels. More megapixels mean more detail at large print sizes, not better pictures; light, lens and technique decide far more.

A larger sensor collects more light in total than a small one for the same framing, at the same f-number and shutter speed, which usually means less visible noise. That is the real difference between sensor sizes. ISO does not make the sensor more sensitive. It sets how much the signal is amplified after the light has been collected.

The processor and buffer

The processor turns the sensor’s signal into a picture: it applies white balance, sharpening, noise reduction and colour for a JPEG, or packs the raw data for you to process later. It also runs autofocus, metering, video and the menus. Each new frame waits in the buffer, a small block of fast memory, until the card has written it. When you hold the shutter button in a long burst, the buffer fills and the frame rate drops until the card catches up. A faster card empties it sooner.

Dark spots in the same place on every picture are dust on the sensor. How to clean your camera’s sensor starts with confirming it is dust and works up from the gentlest method.

DSLR, mirrorless and phone: which parts each one has

All three share the lens, sensor and processor. The difference is how the image gets to your eye. In a DSLR, the mirror reflects light up into a pentaprism (a solid glass block) or a pentamirror (lighter, a little dimmer) and out through an optical viewfinder. When you press the shutter button, the mirror flips up, the view goes dark for a moment, and much of the clunk you hear is the mirror. A mirrorless camera has no mirror; the sensor sees light all the time and shows it on a small screen in the viewfinder or on the rear screen. A phone is a mirrorless camera shrunk down, with very small sensors and a great deal of processing.

Part	DSLR	Mirrorless	Phone
Interchangeable lens	Yes	Yes	No, several fixed lenses
Adjustable aperture	Yes, in the lens	Yes, in the lens	Usually no, fixed
Mirror and pentaprism	Yes	No	No
Viewfinder	Optical	Electronic on most, rear screen only on some	Screen only
Mechanical shutter	Yes	Yes, though some bodies are electronic only	No, electronic
Autofocus	Usually a separate sensor fed by a small secondary mirror	Read from the main sensor	Read from the main sensor
Preview of exposure and white balance	Only in live view	Yes, by default	Yes

That last row matters. An optical viewfinder shows the scene itself, so it cannot preview brightness. An electronic one shows what the sensor will record, so a too-dark exposure looks too dark before you press the button.

Trying to decide between the designs? Mirrorless vs DSLR compares size, viewfinders, focusing and battery life, and smartphone vs camera compares image quality, creative control and convenience.

Sides and base: ports, card slot, battery and tripod socket

The sides carry flaps over the ports: usually a USB port for transfer and, on many cameras, charging; often a video output; and sockets for a microphone and headphones on cameras made for video. The card slot door is on a side or in the grip, and cameras with two slots can record to both at once as a backup.

The battery usually lives in the base or grip. Batteries give fewer shots in the cold, so keep a spare warm in a pocket. The tripod socket is a threaded hole in the base, normally under the lens axis or close to it, so the camera balances on the head.

Common mistakes and misconceptions about camera parts

• “The aperture is in the camera.” It is in the lens. Change lenses and you change the range of apertures available.
• “A mirrorless camera has no shutter.” Most have a mechanical shutter as well as an electronic one. Only the mirror is missing.
• “The click is the shutter.” On a DSLR much of it is the mirror. An electronic shutter makes no sound at all unless the camera plays a fake one.
• “The diopter focuses the picture.” It only matches the viewfinder to your eyes. Set it until the viewfinder text is crisp, then judge focus on the screen at high zoom.
• “The mode dial changes how the photo looks.” In P, A, S and M it only decides who picks the settings. The same aperture, shutter speed and ISO give the same picture in any of them.
• “More megapixels make better photos.” They allow bigger prints and heavier crops. They do not add light, sharpness from a soft lens, or steadiness.
• Covering something with a finger or strap. A finger across the lens front, the flash or the autofocus assist light causes odd exposure and focus. Check your grip each time you pick the camera up.
• Changing lenses with the mount facing up. Dust falls straight onto the sensor or mirror. Switch off, point the mount down, and be quick.

Try this: find every part, then see it in a photo

Ten minutes, any camera with a removable lens. With a phone, do steps 1, 5 and 6 only.

1. Lay the table at the top of this page beside the camera. Find each external part, then close your eyes and find the shutter button, mode dial, command dials and diopter by touch.
2. Switch the camera off, point the mount downward and take the lens off. On a DSLR you will see the mirror. On a mirrorless camera you will see the sensor or, on some models, the closed shutter curtain. Do not touch either. Put the lens back.
3. Open the card and battery doors and find the tripod socket underneath.
4. Look through the viewfinder and turn the diopter until the numbers are sharp.
5. Set aperture priority and f/16 (or the largest f-number your lens allows), look into the front of the lens and take a picture. On a DSLR you will see the blades snap down to a small opening for an instant, because the lens stays wide open between shots to keep the viewfinder bright. On a mirrorless camera, depending on the model, the blades may already be closed down while you compose or may close only for the shot.
6. Photograph a bright point light, such as a streetlamp or the sun just peeking past an edge, once at the widest aperture and once at f/16. Do not look at the sun through an optical viewfinder.

How to judge it: the f/16 frame should show a star of rays around the light and the wide-open one should not. Count the points: a lens with an even number of blades gives that many, and one with an odd number gives twice as many. If you can name the part that made each difference, you know your camera.

Want bolder stars from every light? How to shoot a star-shaped lens flare covers how the blades make the star, which apertures to use, and the light sources that give the cleanest rays.

Want to check you can name each part and what it does? Try the camera anatomy quiz.

Frequently asked questions about camera parts

What are the main parts of a camera?

The lens, aperture, lens mount, shutter, sensor, processor, viewfinder, rear screen, shutter button, mode dial, command dials, memory card and battery. The lens and sensor make the image. The others control it, show it or store it.

What are the parts inside a camera?

A sensor, a shutter of some kind, an image processor and a buffer are inside almost every digital camera. A DSLR also has a mirror and a pentaprism or pentamirror. Many cameras have a stabilization unit, and the lens contains its own glass elements and aperture.

What is the body of a camera?

The body is the camera without the lens. It holds the sensor, shutter, processor, screens, controls, card slot and battery, and the lens attaches to it at the mount.

Does a mirrorless camera have a shutter?

Yes. Most have a mechanical focal-plane shutter and an electronic shutter, and you choose between them in the menu. A few bodies are electronic only.

Does a phone have the same parts as a camera?

It has the core ones: lenses, sensors, a processor and a screen. It usually lacks an adjustable aperture, a mechanical shutter and a mirror, and makes up for its tiny sensors with heavy processing. See phone camera settings for the controls it does give you.

Why does my camera make two clicks?

On a DSLR, the mirror flips up and the shutter opens, then the shutter closes and the mirror drops back. On a mirrorless camera, the open shutter closes before the exposure and reopens after it. An electronic shutter is silent.