Before we discuss Micro 4/3 we need to learn a bit about how the 4/3 system started. The 4/3 system was developed from the ground up to be a digital only camera system. It is also an “open system” meaning that multiple manufacturers can produce lenses and cameras for the system that can be interchanged. The original 4/3 cameras were similar to the DSLRs that Canon and Nikon make, and complete with optical viewfinders.
Olympus, and to a smaller extent Panasonic, sold DSLRs in the original 4/3 system, but they found it hard to make inroads against Canon and Nikon. In order to fight back they introduced the Micro 4/3 system in 2008. Unlike the previous cameras, the Micro cameras removed the mirror box. The mirror box is what sits behind the lens on a SLR and sends the image from the lens up through the optical viewfinder. Without the mirror box Micro 4/3 cameras can be much smaller than their DSLR counterparts, and indeed this is one of their biggest advantages. For example, Panasonic’s GM-1, despite its large sensor and ability to change lenses, is about the size of a Sony RX100.
Initially the system had a modest selection of lenses and cameras to choose from, however in recent years the choices have multiplied significantly. The camera bodies range from small, simple, and affordable all the way up to professional models that look like, and handle like, a mini DSLR. Lens choices are abundant and since you can use a Panasonic lens on an Olympus body, and vice versa, your selections multiply. There are lenses available for almost any application, and the high-end lenses rival those from Canon and Nikon’s professional lines. One thing to be mindful of is the Micro 4/3 lens crop factor of 2x. Simply put, when picking a lens you need to multiply the focal length by 2 to get the focal length equivalent on a 35mm camera. For example a 12-50mm lens would really give you a 24-100mm field of view. A benefit this high crop factor brings is modestly sized lenses that can deliver serious telephoto reach.
What Makes a Micro 4/3 Sensor Different than a DSLR?
A Micro 4/3 sensor is significantly larger than those of most compact cameras, but is smaller than the APS-C sensors that Canon, Nikon, and Sony use in some cameras. The relatively large 4/3 sensor allows Micro 4/3 cameras to shoot at high ISO speeds with low noise levels and create shallow depth of field with the right lens attached. That same sensor is also used for the Micro 4/3 camera’s contrast detection autofocus system, which is the speedy, consistent, and very accurate.
All of your composing on a Micro 4/3 camera will be done using live view through a screen on the back of the camera or, on some models, an electronic viewfinder. As mentioned earlier, since there are no mirror boxes on Micro 4/3 cameras none of them have an optical viewfinder, which some people view as a deal-breaker.
Micro 4/3 cameras are an excellent choice for a lot of people. From those stepping up from a compact camera, to those demanding professional features and photo quality, there is something in the Micro 4/3 system for everyone.
If you're having a difficult time deciding between a Micro 4/3 camera and a DSLR, read this post.