Micro Four Thirds
Before their was Micro Four Thirds, there was just plain old Four Thirds.
The Four Thirds format was a system developed by Olympus that they leveraged for their line of digital SLR cameras.
Essentially, Four Thirds cameras included sensors that were just a bit smaller than regular digital SLR sensors.
Since larger sensors do yield higher-quality images (especially in low available light) this seemed like a questionable choice - until you realize the benefit.
With just a slight reduction in the size of the sensor, Olympus was able to produce some of the smallest and lightest digital SLR cameras on the market.
The line of Olympus Four Thirds cameras were very easy to carry around - and many pro photographers will tell you that a camera is only useful if you can carry it at all times. If you always leave your camera at home because it's too big and bulky you won't be able to capture that once-in-a-lifetime shot when you come upon it.
So the Four Thirds format made the Olympus cameras extremely portable...but there was another additional benefit.
It's All in the Lens Mount
For years, camera manufacturers got people to buy into an SLR system not because of the cameras but because of the LENSES.
Having a good selection of lenses is crucial - especially for advanced amateur and pro photographers - when it comes to selecting a camera system.
Since superior lenses often cost as much if not more than the camera body, once you buy a set of lenses, you're locked into that camera-maker for good.
This inability to switch one manufacturer's camera body for another is due to the custom connection between lens and camera - also called a lens mount.
Simply put, every manufacturer's lens mount is different, which prevents you from swapping lenses and cameras at will.
Canon lenses are matched to Canon cameras, and cannot be used on other brands. The same applies to Nikon, Pentax and Sony.
However, the Four Thirds format sought to change this pattern.
A Four Thirds lens mount is standard — this means that any camera that calls itself Four Thirds will work with any Four Thirds lens, regardless of the lens manufacturer.
Thus far, only Olympus and Panasonic have adopted the standard, so it's no common thing...but the idea does have promise.
Since you can already use Panasonic lenses on Olympus cameras and vice versa, it's quite interesting to imagine a day when any lens could be used on any camera body.
Let's get back to our discussion of Micro Four Thirds - after all, that's what this page is about right?
Having had success with their line of Four Thirds digital SLR cameras, Panasonic and Olympus decided to remove the last remaining obstacle in the way of a small-sized camera with DSLR image quality: the viewfinder.
The viewfinder in all digital SLR cameras is made up of a group of mirrors called a Pentaprism or Pentamirrors.
These mirrors take up quite a bit of space and they increase the bulk and weight of all digital SLR cameras.
By eliminating this one feature, Panasonic and Olympus were able to dramatically shrink the size of their cameras: they made their Four Thirds cameras "Micro".
Here's the key point: the size of the sensor didn't change.
A Micro Four Thirds camera is not all that much larger than a compact digicam, yet it's able to replicate the higher image quality you can achieve with a digital SLR.
Most Micro Four Thirds cameras also include a video capture feature, something that's lacking on many digital SLR cameras.
Even MORE Lens Options
If the idea of an exceptionally portable digital SLR isn't appealing enough, then consider this: Micro Four Thirds cameras open the door to even MORE lens options.
First, an important note: the lens mount on a Micro Four Thirds camera IS smaller than even the standard Four Thirds lens mount.
This means that if you want to use Four Thirds lenses with a Micro Four Thirds camera, you'll have to purchase a special lens mount adapter.
However, it's this same lens mount adapter concept that opens the door to a world of other lens possibilities. For example, now you can buy a lens mount adapter to attach a Canon or Nikon lens to a Micro Four Thirds camera.
When an adapter is used, the lens loses functionality — the most common issue is that the lens can't use autofocus. Another is that the lens will only use its widest aperture, and you can't change the aperture of the lens using the camera body.
These might seem like big issues at first, but if you have a collection of lenses for other cameras and decide on an Olympus or Panasonic Micro Four Thirds, those lenses don't have to sit around gathering dust.
What About Other Manufacturers?
You'll note that the name of this web site is the Mirrorless Camera Guide, not the "Micro Four Thirds" Guide — there's a good reason for that.
Now that other camera-makers are releasing their own models, a slew of terms has cropped up to describe these types of cameras:
I settled on the name "Mirrorless Camera" since that's how I think of them: digital SLRs minus the mirrored viewfinder.
Regardless of what you call them, these cameras are here to stay: their combination of superior image quality and exceptional portability make them appealing to a broad range of photographers.
Mirrorless Camera Terms