Runs a sensor around 1.7 times the area of full frame for files meant to be printed large.
also: digital medium format, large sensor camera
The basics
What to know about digital cameras
You can measure what it does
A digital camera records light on a sensor you can look up and measure. That measurement is the gap between it and the phone in your pocket. Full frame names a sensor of 36 by 24 mm, the same rectangle 35 mm film used, giving 864 square millimeters of collecting surface. APS-C, the common smaller format, runs near 23.5 by 15.6 mm, and micro four thirds measures 17.3 by 13 mm. A 1 inch type sensor is really 13.2 by 8.8 mm, because that name describes an old vacuum tube rather than anything you can put a ruler on. The main sensor in a good phone covers about 70 square millimeters. Bodies then split two ways: interchangeable lens cameras, where a mount lets you swap glass, and fixed lens cameras, where the lens is built in and the choice is permanent.
Sensor area is the mechanism
Sensor area is the mechanism behind nearly everything you will notice. Double the collecting surface and you double the light, which photographers count in stops, one stop being one doubling. Full frame sits roughly 1.2 stops above APS-C, 2 stops above micro four thirds and close to 3 stops above a 1 inch sensor. That budget keeps your shutter fast enough to freeze a child crossing a living room before the picture breaks into colored speckle. Sensor size also rescales your lenses through a figure called crop factor, 1.5x on APS-C and 2x on micro four thirds, so a 50 mm lens frames like a 75 mm on one and a 100 mm on the other. Depth of field, the thickness of the zone that comes out sharp, scales the same way. Small sensors hold more of a scene in focus at the same setting. This helps a landscape and fights you in a portrait.
The lens decides the rest
Glass decides the rest. Aperture is written as an f-number, the focal length divided by the width of the opening, so a lower number means a bigger hole. An f/1.8 lens passes about four times the light of one at f/3.5, a gap of two stops, and that is why a fast prime, meaning a lens with one fixed focal length and a wide maximum aperture, beats a kit zoom after sunset. Stabilization buys shutter speed instead of light: rated at 5 stops it lets you hand hold at 1/8 second where 1/250 was needed, and it does nothing about a subject moving on its own. Megapixels draw more attention than they earn, since 24 of them means 6000 by 4000 pixels, a 20 inch print at 300 dots per inch. Nearly three times what a 4K screen can show. Autofocus is where the last decade of progress actually landed, with detection points spread across the sensor that find an eye, an animal or a vehicle and hold it while both of you move.
Match the body to the job
Match the body to the job. Mirrorless Cameras are the mainstream answer now and take almost every lens still being designed. DSLR Cameras, where a reflex mirror throws the view up into an optical finder, make their case secondhand, at roughly half the price of the mirrorless pair. Compact Cameras ride in a coat pocket, Bridge Cameras reach 600 to 1200 mm of equivalent zoom in one sealed piece, Action Cameras go underwater and onto helmets, Instant Cameras put a print in someone's hand in 90 seconds, and Medium Format Cameras serve studio and landscape work printed large. Then think about the phone: in daylight, at one focal length, for pictures that live on screens, it stacks several exposures in software and often beats a single frame off a big sensor in harsh contrast. A camera pulls ahead when the light drops, when the subject is fast, when you need reach past about 5x, when you want one face sharp against a dissolved background, and when the file has to print past 16 inches.
The mount is a decade long choice
Every gain bills you in weight, money or freedom. The mount is the decade long commitment. Bodies lose 40 to 50 percent of their value in three years while good lenses keep most of theirs. So people end up owning more glass than camera. Mirrorless mounts sit 16 to 20 mm from the sensor and reflex mounts sit 44 to 47 mm. An adapter can carry a reflex lens forward onto a mirrorless body and never the other way. Bulk is the second bill, since a full frame body with a constant f/2.8 standard zoom lands at 1.5 to 1.9 kg. Mirrorless bodies also drink batteries, because the viewfinder is a small screen running the whole time: 350 to 700 frames a charge against 900 to 1500 from a reflex body whose optical finder needs no power at all.
Put your eye to the viewfinder
Judge a body on what the headline spec hides. Put your eye to the viewfinder first, because 2.36 million dots looks coarse and smears in dim light, 3.69 million is the comfortable middle, and 5.76 million reads like a window. Ask how quickly the sensor is read out: a slow 1/30 second scan tilts vertical lines when you pan, an effect called rolling shutter, while a stacked sensor clears the frame in about 1/180. Find out whether 4K comes from the full sensor width downsampled from 6K or from a cropped, line skipped patch, since the second is visibly softer. Two card slots matter on the day one card fails. On anything used, ask for the shutter count, because mechanical shutters carry a rating of 100,000 to 500,000 actuations.
Humidity ruins more than shooting
Storage ruins more cameras than shooting does. Past roughly 60 percent relative humidity in a warm room, fungus spreads across internal lens glass in a single season and etches the coating for good, so keep the kit in a sealed box with silica gel at 40 to 50 percent instead of a padded bag in a cupboard. Leave batteries near half charge between outings, and reach for a hand blower rather than canned air on the sensor, whose propellant leaves a film that then needs a wet swab.
Buyer checklist
Before you buy digital cameras
Electronics combine hardware, software and services. Compatibility and support life matter as much as the headline specification.
01
Map the whole setup
Confirm the ports, operating system, network, accessories, apps and services the product must work with.
02
Check the support period
Look for a clear security and software-update policy, especially on connected products and discounted older models.
03
Separate included from subscription
Find out which recording, storage, analytics, content or remote features need an ongoing payment.
04
Plan for repair and data
Check battery and spare-part service, warranty handling, account controls and how personal data can be exported or deleted.
Weigh the whole kit rather than the body. A full frame camera with a constant f/2.8 standard zoom sits at 1.5 to 1.9 kg, an APS-C body with its kit zoom at 800 g to 1 kg, and a micro four thirds pair at 600 to 800 g. Hang your candidate combination from your neck and walk around for an hour, because the camera you leave at home has no image quality at all.
Measure your hand against the grip before ordering. Bodies under about 60 mm from base plate to top leave your little finger hanging off the bottom, which becomes a cramp after 200 frames. Hold the body with the heaviest lens you expect to own, and if your fingertips press into the lens barrel you need a grip extension or a taller body.
Note the filter thread diameter printed on every lens you plan to buy, given in millimeters and often 49, 58, 67, 72 or 82. Standardize on the largest, buy that one size of polarizer and neutral density filter, then use step up rings for the smaller lenses, since a good filter can cost more than a used lens.
Match the card to the video mode, not to the camera. The V rating is a guaranteed sustained write speed in megabytes per second. V30 covers 4K up to roughly 200 Mbps while 10 bit footage at 400 Mbps needs V60 or better, or a CFexpress card. Read the slot too: a UHS-I slot caps near 100 MB/s whatever card you push into it.
Count your longest day in frames and divide by the rated capacity. Mirrorless bodies are rated at 350 to 700 shots per charge under the standard industry test, reflex bodies at 900 to 1500. A wedding or a match runs past 1200. Carry two spares in winter, since capacity drops sharply below 5 C.
Check that a tripod plate clears the battery door before you buy one. The thread is 1/4 inch with 20 threads per inch on nearly every body, so plates fit. But a plate covering the door means unscrewing it every battery change. Measure your longest lens as well, because a 200 mm zoom is around 20 cm and will not stand upright in a shallow bag.
Care
Caring for digital cameras
Store the kit dry, since humidity ruins more lenses than drops do. Above roughly 60 percent relative humidity in a warm room, fungus spreads across internal glass in one season and etches the coating permanently. A sealed box with silica gel held at 40 to 50 percent costs little. A cupboard and a padded bag hold moisture against the gear.
Clean the sensor with a hand blower first and nothing else. Canned air fires propellant that leaves a film needing a wet clean, and its pressure can disturb the shutter blades. If the blower fails, use a swab sized to your sensor width with two drops of the correct fluid, one pass in each direction, and stop there.
Park batteries near 40 to 60 percent charge when the camera goes unused for a month, and take them out of the body. Cells held full and warm lose capacity fastest. A battery left in a camera keeps a small drain running that flattens it and shortens its life.
Format cards in the camera after every offload instead of deleting files on a computer. Formatting rebuilds the file structure the camera expects and clears the fragmentation that stalls a buffer mid burst. Retire a heavily used card after two or three years, because flash memory wears out quietly and fails all at once.
Update firmware on your lenses as well as the body, which is the step nearly everyone skips. Lens firmware fixes autofocus hunting and stabilization conflicts, and body firmware regularly adds subject detection that did not exist at launch. Charge the battery fully first, since an update interrupted halfway can mean a service visit.
Change lenses with the body pointed down and switched off, in still air. Gravity carries falling dust away from the sensor, and a powered sensor holds a static charge that pulls dust toward it. Wipe the gold contacts on the mount with a dry cloth twice a year, since a smeared contact reads as a broken lens.
Questions
Common questions
How many megapixels do I actually need?
24 is the sensible default. It gives 6000 by 4000 pixels, a 20 inch print at 300 dots per inch, and enough margin to crop to half the frame and still fill a 4K screen. Move up to 45 or 60 only if you crop hard for wildlife or print very large, because those files run three times bigger and slow every step after the shutter.
Full frame or APS-C for a first serious camera?
APS-C for most people. Full frame collects about 1.2 stops more light and blurs backgrounds more easily at the same framing, which matters in dim rooms and for portraits. It also costs more in every direction, since a full frame kit with a standard zoom runs 1.5 to 1.9 kg against 800 g to 1 kg. Put the saving into one fast prime lens.
Do I need a camera at all when my phone shoots this well?
Not always. In daylight, at one focal length, for photos that stay on screens, a phone stacks several exposures in software and can beat a single frame from a large sensor. Buy a camera for the five things a phone cannot do: reach past about 5x, fast subjects in dim light, shallow focus on objects and animals, prints past 16 inches, and long video with an external microphone.
Mirrorless or DSLR?
Mirrorless if you are buying new, because nearly all current lens development goes into those mounts. A reflex body remains a sound used buy: its optical finder needs no power and returns 900 to 1500 frames a charge, and a sealed body with a fast prime costs about half the mirrorless equivalent. Get the shutter count in writing and test focus at the widest aperture.
Should I take the kit lens or buy the body alone?
Take the kit zoom the first time. Bundled it adds a fraction of its standalone price, covers roughly 24 to 70 mm equivalent, and tells you which focal lengths you really use. Read that off your first 500 photos, then buy one fast prime near that number, since an f/1.8 prime passes about four times the light of a kit zoom at its f/3.5 end.
How high a shutter count is too high on a used body?
Stay under about 40 percent of the rating. Mechanical shutters are rated for 100,000 to 500,000 actuations, and consumer bodies sit at the low end of that. A 200,000 count on a body rated for 500,000 is fine, while the same figure on one rated for 150,000 means a repair is due. Check the grip rubber and card door for wear too, which often tells you more.
Which memory card do I need for 4K video?
V30 is the floor. The V number is the guaranteed sustained write speed in megabytes per second. V30 holds 30 MB/s and covers 4K up to roughly 200 Mbps. Ten bit footage at 400 Mbps needs V60 or V90, and the highest bitrate modes need CFexpress. Check the slot as well, since a UHS-I slot stops near 100 MB/s regardless of the card.
Does in-body stabilization let me leave the tripod behind?
For still subjects, mostly. Five stops of correction takes a handheld shot from 1/250 second down to about 1/8, which covers interiors and streets at dusk. It cannot fix a moving subject, because that blur comes from them rather than from your hands. Exposures past one second, focus stacking and precise panoramas still need three legs.
