Pentax does mirrorless a bit differently. After introducing the smallest interchangeable-lens mirrorless model (with the smallest image sensor) in the Q, they followed up with the largest mirrorless model without a built-in eye-level EVF in the K-01.

Samsung’s mirrorless cameras all feature big APS-C image sensors and are available in "mini-DSLR" and "flat" form factors.

The middle model in Samsung’s Wi-Fi NX lineup, the NX210 offers the same 20.3-megapixel image sensor, built-in Wi-Fi capabilities and shooting features as its siblings.

The most compact member of Samsung’s current NX family, the NX1000 shares the 20.3-megapixel image sensor and built-in Wi-Fi capability of the NX20 and NX210, but measures just 4.5×2.5×1.5 inches and weighs just 7.8 ounces.

Taking over from the NEX-C3 as the entry-level model in Sony’s mirrorless line, the NEX-F3 incorporates a big, 16.1-megapixel APS-C HD CMOS sensor that delivers excellent image quality and video. Besides simple operation, features include Auto HDR, Anti-Motion Blur, Sweep Panorama, 3D Sweep Panorama, focus peaking (for easy manual focusing) and 15 in-camera effects.

While those moving up to a mirrorless interchangeable-lens camera from a point-and-shoot are happy to use the LCD monitor as their composing device, some longtime DSLR (and film SLR) users find it awkward.

We’re into the third generation of NEX now, with Sony’s successor to the NEX-5N, the NEX-5R, bringing a number of improvements on the earlier model.

Nikon entered the mirrorless interchangeable-lens marketplace last year with the Nikon 1 J1 and Nikon 1 V1 models, very compact cameras built around the same 10-megapixel CMOS sensor in a new CX format.

Olympus’ first mirrorless interchangeable-lens cameras were inspired by the company’s popular PEN 35mm compact cameras of the 1960s.

Canon’s long-anticipated mirrorless interchangeable-lens camera finally materialized in Summer 2012.

There’s no question that mirrorless, interchangeable-lens cameras are increasingly popular—more mirrorless models were introduced last year than traditional DSLRs.

For many years, the two most popular types of digital cameras have been compact models and digital SLRs. Each offers advantages over the other.