The basic idea behind a mirrorless camera 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. They can also be considered compact interchangeable lens cameras, hybrid cameras, or compact system cameras.
In 2008, Panasonic introduced the first mirrorless interchangeable-lens camera, the Lumix DMC-G1 – containing the same Four Thirds System image sensor used on Four thirds System DSLRs. Mirrorless interchangeable-lens cameras came into being because many felt that DSLRs were too bulky and cumbersome to which can become a hassle to carry around. The mirrorless camera provides DSLR quality in smaller, lighter packaging. The mirrorless camera removes the mirror box and prism finder from a DSLR-style form factor, and replaces it with an electronic viewfinder.
Most of the early mirrorless cameras were aimed at people moving up from a point-and-shoot, who wanted flexibility of interchangeable lenses and the boost in image quality inherent in larger sensors. As of today there are a great variety of mirrorless models that can provide great quality to those seeking to have a camera that will produce quality photos as those that are produced from their DSLR.
Outdoor Photographer describes the main difference between the smaller, mirrorless cameras and actual DSLRs (besides the size) is the electronic viewfinder (EVF) that replaces the DSLRs optical viewfinder. The EVF shows you the image produced by the image sensor, as it will be recorded, allowing you to see the effects of white balance, exposure compensation, special effects and the like live in the viewfinder. EVFs also can display more information, including histograms and focus peaking (which highlights in-focus edges in teh image for easier manual focusing), and you can zoom the image to really examine it. EVFs also provide more eyepiece dioptric correction – where you might need glasses with your DSLR, you might not with an EVF camera.
Another way to look at it is that what the EVF shows is essentially a relatively low-res video on a half-inch screen, like a DSLR finder shows the image from the lense with no electronic interference.
What’s your experience with mirrorless, and how does it work with your photography style?