Gizmodo Camera Buying Guide: Mirrorless Cameras Explained

Mirrorless cameras -- aka compact system cameras -- arguably have the photographic features of a full-sized digital SLR in a compact, attractive body. They're portable and powerful, but there are a few key features that separate mirrorless cameras from the rest of the pack. Don't really know what any of this means? Read on.

What's In A Name?

Mirrorless cameras go by any of a few different names. You might see them called compact system cameras (CSCs), mirrorless system cameras (MSCs), electronic viewfinder with interchangeable lens cameras (EVILs), or digital or mirrorless interchangeable lens cameras (MILCs). Basically, a mirrorless camera is one that doesn't have a mirror or mirror box inside its body, reflecting light through the lens to an optical viewfinder (like the one on top of a digital SLR).

The mirrorless camera category includes models like the full-frame Sony Alpha A7R, the waterproof Nikon 1 AW1, the miniscule Panasonic DMC-GM1, and the DSLR-esque Olympus OM-D E-M1. Mirrorless cameras span a huge range of sizes, designs and mission statements; but if you don't like the look of a digital SLR, but want something more versatile than a point-and-shoot compact camera, a mirrorless shooter is the way to go.

What Are The Advantages?

Mirrorless cameras are simpler, smaller, lighter and as a result, even more versatile as a digital SLR. The controls are much the same. They have a lens at the front, sensor inside, and a screen and (occasionally) a viewfinder at the back.

When you switch the camera on, it displays a live view of what the camera is seeing on the back screen or viewfinder. Having the touchscreen switched on does use up battery power, but you're able to see exactly what your photo will turn out to be thanks to features like Live View. Using an electronic viewfinder also gives you the familiar feeling of putting a camera to your eye to take a photo, but is more versatile in low light.

These pint-sized cameras are pocketable with the right lens (often referred to as pancake lenses), or are light enough to wear all day on a neck strap. Don't let size fool you, however: these cameras pack large, high quality imaging sensors. And having the option to change your lens is a godsend, too -- you can do almost everything with a mirrorless camera that you can with a bulky brute of a digital SLR.

Bodies: Smaller, Sleeker

Digital SLRs are big, there's no denying it. Mirrorless cameras can be much, much smaller than DSLRs, without sacrificing features. Take the Olympus E-PM2, for example. It's a third less wide, half as tall, and more than half the thickness of the Olympus E-5 DSLR, but it uses the same imaging sensor and is every bit as powerful.

Less space for legacy features means more room for fancy circuitry. Sony, for example, fits NFC, Wi-Fi, Full HD movie recording, a tilting 3-inch screen, and a 16-megapixel sensor into the NEX-5T, a camera that's no wider or taller than an iPhone. And this is a theme that runs throughout the mirrorless camera line-up -- they're all packed with fancy functions despite being tiny.

Sensors: Bigger Than You Think

Because they don't need all that legacy hardware like a mirror box, there's a lot of room inside the body of a mirrorless camera. That means camera manufacturers can fit in a large imaging sensor, often just as large as in a bulky digital SLR.

Panasonic and Olympus mirrorless cameras are members of the Micro Four-Thirds family (with a 18x13.5mm sensor); Canon, Fujifilm and Sony's mirrorless cameras have large APS-C-sized sensors, like most digital SLRs (around 26x15mm); Nikon and Pentax have opted for smaller bodies and smaller sensors in their respective 1 (15.8x13.2mm) and Q cameras (9.5x7.6mm).

Some stand-outs exist, too. The Leica M9 and M are technically mirrorless cameras with full-frame (36x24mm) sensors, and Sony has the Alpha a7 and a7R -- also full-frame, with extremely large and high-resolution sensors inside their tiny shells.

More: Mirrorless Camera Lenses, Brand By Brand

Viewfinders: Usually Electronic

No mirror means no light bouncing through the lens and up into an optical viewfinder. Instead, the simpler solution is for most mirrorless cameras to use a tiny LCD or OLED screen as a viewfinder, displaying a live read-out from the camera's digital sensor.

Electronic viewfinders (EVFs) give a more accurate view of what your picture is going to look like, but a less true-to-life image than an optical viewfinder. They're a necessary compromise that nonetheless has some significant technical advantages -- like being brighter and more useful in low light than optical.

Exceptions do exist, like the Fujifilm X-Pro1 -- which has an optical viewfinder with an electronic overlay -- but these are few and far between.

Lenses: Lighter, Brighter, Faster

Mirrorless cameras are just like digital SLRs -- you're not stuck with any one lens, so you can build a collection and use whichever is most appropriate for the photo you want to take. There are dozens of mirrorless lenses available.

Because mirrorless cameras don't have a mirror, this means a short flange focal distance -- between the rear of the lens and the front of the sensor. Lenses for mirrorless cameras are smaller, shorter and lighter, without sacrificing image quality. You can build a full kit of several mirrorless camera lenses for the weight, size and price of a single telephoto lens for a digital SLR.

Being mirrorless also helps cut down on the weight of glass elements within lenses, too. This helps speed up autofocus times, and enables nifty features like full-time continuous autofocus, which is very useful for budding videographers and home movie fanatics.

Mirrorless lenses also have just as many features as their bigger counterparts. You can get super-bright prime lenses, fast constant-aperture standard and telephoto zooms, and ultra-compact collapsible wide angle zooms. Many lenses have image stabilisation, and some camera bodies have IS built in -- so even old lenses get a helping hand.

Next up we'll look at compact system camera lenses. Stay tuned.

More: Gizmodo Camera Buying Guide: Which Digital Camera Is Right For You?