Mirrorless cameras have come a long, long way over the past few years. The basic idea is eliminating the mirror and optical viewfinder that you'll find in an SLR in order to keep the size and weight of the camera down. At first, no one really knew what to call them—so you may have heard about compact interchangeable lens cameras, hybrid cameas, compact system cameras, or something else. But rest assured, they're all pretty much the same thing.
Early models fulfilled the promise of SLR-like image quality in a smaller form factor, but suffered from slow autofocus and limited burst shooting. Those days are, for the most part, over. Entry-level models can still be a little pokey in terms of focus, but as soon as you get into the midrange you'll find that many models match SLRs in focus speed, and better them when focusing during video recording. Because of their slim design, these cameras give you the option of buying modern native lenses or mounting older SLR and rangefinder lenses via a simple adapter.
Available Camera Systems
The first models to hit the market were part of the Micro Four Thirds system, a mount and lens system that's shared by Olympus and Panasonic cameras. Those were soon joined by Sony and Samsung, and later by Pentax, Fujifilm, and Nikon—and each of those companies uses its own proprietary lens system.
Late to the game is the brand that is synonymous with cameras in many minds, Canon. Its EOS M debuted to a cool reception in the United States, and the company didn't market the second version of the M here. But it reintroduced the system to the US with the EOS M3 and has continued to roll out new cameras and lenses. It appears as if Canon is once again committed to grabbing a piece of the mirrorless market.
See How We Test Digital Cameras
Because development has not been tied to legacy systems that are built around 35mm film, sensor sizes vary. Of currently available models, the Nikon 1 system use 1-inch image sensors, which are the smallest you'll find in a mirrorless camera. They match the size of sensors found in high-end point-and-shoot and bridge cameras. The small sensor size requires you to multiply lens focal length by 2.7 in order to couch it in the industry standard full-frame equivalent nomenclature. A 10mm lens on a 1-inch camera matches the field of view of a 27mm lens on a full-frame system.
The Micro Four Thirds system is next up in size. If you want to get an idea of how the field of view of Micro Four Thirds lenses compares with 35mm film, you'll want to double the focal length; a 25mm lens on a Micro Four Thirds camera matches the field of view of a 50mm lens on a full-frame DSLR. The sensor aspect ratio is also different—it's 4:3, like an old TV, rather than the 3:2 ratio of APS-C and full-frame systems.
Like most consumer DSLRs, systems like the Fujifilm X, Leica T, Sony E, and Canon EOS M use APS-C image sensors. They enjoy a 1.5x multiplication factor compared with full-frame cameras, a figure that anyone who has shopped for an APS-C DSLR is familiar with.
Fujifilm and Hasselblad have both announced medium format mirrorless systems. Both the Fujifilm GFX 50S and Hasselblad X1D use 44 x 33mm image sensors, requiring you to multiply by 0.78x to get the 35mm full-frame field of view. A 65mm medium format lens roughly matches a 50mm full-frame lens in field of view, but like Micro Four Thirds the medium format systems use a 4:3 aspect ratio.
At one point Samsung was developing two mirrorless sytems—the APS-C NX and the 1-inch NX Mini. But Samsung is no longer making new cameras or lenses for either system. If you come across a deal on a Samsung mirrorless camera, understand that you won't be able to get new lenses or accessories for it in the future.
Similarly, it appears that Ricoh Pentax is out of the mirrorless game, at least for the time being. It doesn't have a model from its Q system, a tiny camera line that utilized point-and-shoot sized image sensors, for sale on its Web site.
Full-Frame
Sony and Leica are the only companies that currently offer full-frame mirrorless cameras. Sony has a trio of models in the Alpha 7 II line, and Leica offers both the autofocus SL and the manual focus M rangefinder series.
The Sony system uses the same physical lens mounts as APS-C Sony bodies, and if you mount a lens that's designed for an APS-C Sony body, the image will automatically be cropped to compensate for the smaller field of view produced by the lens. Likewise, the Leica SL can mount lenses for its TL APS-C system in the same manner.
Leica M rangefinder cameras have been around longer than most SLR mounts—for more than 60 years—and have long utilized a fixed optical viewfinder with an optical rangefinder to focus and frame shots. The latest digital iteration, the M (Typ 240), adds Live View and video recording, but in many ways it still handles like a camera from the 1960s. Old school shooters appreciate that, but they pay a premium for the privilege of using a niche, retro camera.
Mirrorless cameras are better than they've ever been before, and we've highlighted the best models that we've tested here. Most offer excellent image quality, quick autofocus, and a wealth of lens options. But if you're not ready to make the move away from a traditional optical viewfinder you'll still want a DSLR. Check out The Best DSLRs for a look at our top-rated standard-size interchangeable lens cameras. Then hit The 10 Best Digital Cameras for our overall favorite models. And take a look at these Beyond-Basic Photography Tips for ideas on how to take even better photos.