What is a mirrorless camera?

Watch video: What is a mirrorless camera? 

Mirrorless cameras are all the rage these days, with “full-frame mirrorless” and even “mirrorless medium format” being buzzwords du jour. But what exactly is a mirrorless camera, and what makes it different from a DSLR?

• See the Digital Camera World A-Z Dictionary of photography jargon

As you’ve probably guessed, the main difference is that a mirrorless camera has no reflex mirror. In a DSLR, a physical mirror is used to reflect an image up to the optical viewfinder; to capture a photograph, the mirror flips out of the way to allow light to hit the image sensor.

With a mirrorless camera, though, the sensor is always exposed to light, enabling it to capture a Live View image without the need for a mirror or optical viewfinder. Instead, this literal 'live view' is displayed on the rear LCD screen or through an electronic viewfinder – which is a miniature LCD or OLED monitor. 

Unlike an optical viewfinder, Live View gives a 'live' preview of the image exactly as it will be exposed, enabling you to see how settings like ISO, aperture and shutter speed will affect your final image before you've even taken it.

The best mirrorless cameras in 2019

Canon and Nikon have finally joined the mirrorless race with their full-frame R and Z systems

Canon and Nikon have finally joined the mirrorless race with their full-frame R and Z systems (Image credit: Digital Camera World)

The lack of a physical mirror to clunk out of the way means that mirrorless cameras can shoot absolutely silently, making them perfect for weddings or other events where noisy shutters are intrusive and unwelcome. 

Removing the mirror also reduces the flange back distance – meaning that the back of a lens element can be much closer to the image sensor. Manufacturers can therefore produce more exotic and high-performance lenses, but it also means that you can adapt a wide variety of old film and lenses – as well as DSLR and mirrorless lenses from other systems. 

Many mirrorless cameras feature in-body image stabilization. This uses magnetic fields to stabilize the sensor and counteract movement or camera shake. It’s common for mirrorless cameras to deliver five shutter stops of image stabilization – ideal for wobbly hands, shooting in low light, or using long lenses. 

And because they dispense with the clunky mirror mechanism and optical viewfinder, mirrorless cameras can be a fraction of the size and weight of their DSLR counterparts, giving fantastic image quality in bodies as small as compact cameras. 

Pioneered by cameras like the Olympus OM-D E-M5, mirrorless cameras can feature incredible in-body image stabilization

Pioneered by cameras like the Olympus OM-D E-M5, mirrorless cameras can feature incredible in-body image stabilization (Image credit: Digital Camera World)

Wait a minute, though – compact cameras don’t have mirrors or optical viewfinders either. Aren’t they mirrorless cameras as well? 

Well, yes – everything from a point-and-shoot to a rangefinder and even your smartphone is technically a mirrorless camera. However, when discussing mirrorless cameras, we’re generally referring to digital interchangeable lens cameras. 

Because of their many advantages, mirrorless cameras are rapidly replacing DSLRs as the technology of choice for consumers and manufacturers alike. They say that less is more, and that’s definitely true when it comes to mirrorless. 

More videos: 

What is depth of field in photography?
What is aperture on a camera?
5 tips for choosing and using… polarizing filters

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James Artaius

The editor of Digital Camera World, James has 21 years experience as a journalist and started working in the photographic industry in 2014 (as an assistant to Damian McGillicuddy, who succeeded David Bailey as Principal Photographer for Olympus). In this time he shot for clients like Aston Martin Racing, Elinchrom and L'Oréal, in addition to shooting campaigns and product testing for Olympus, and providing training for professionals. This has led him to being a go-to expert for camera and lens reviews, photo and lighting tutorials, as well as industry news, rumors and analysis for publications like Digital Camera MagazinePhotoPlus: The Canon MagazineN-Photo: The Nikon MagazineDigital Photographer and Professional Imagemaker, as well as hosting workshops and talks at The Photography Show. He also serves as a judge for the Red Bull Illume Photo Contest. An Olympus and Canon shooter, he has a wealth of knowledge on cameras of all makes – and a fondness for vintage lenses and instant cameras.