Micro Four Thirds: Evolution of the dSLR?

Background

For decades the single lens reflex camera (SLR) has referred to cameras that, with the proper mirrors and/or prisms would allow the photographer to see through the lens to frame the subject and judge focus.  When people talk about SLR cameras they generally think of a big camera where you look through a viewfinder, see through the lens, and when you take the shot, the mirror flips up to expose the image sensor.  Now the new Micro Four Thirds technology used by Olympus and Panasonic is starting to blur the lines of what we call a dSLR (digital single lens reflex) by removing the mirror(s) and prism that add complexity to the dSLR and replacing them with digital components.  Are these new "solid state" cameras still SLR cameras and what benefits do they offer? 

The primary distinction between pocket cameras and dSLR cameras is that the dSLR allows you to physically see through the lens without any conversion of the image to digital format.  That is, the light goes straight through the lens and (after some bouncing around) directly to your eyes, hence the term optical viewfinder.  Most pocket cameras see through the lens too, but they convert that light and display it on an LCD screen on the rear of the camera so in a sense you are not seeing through the lens: you are seeing what the camera sees through the lens.

The Olympus/Panasonic Micro Four Thirds system used in cameras like the Panasonic G1 and upcoming E-series cameras from Olympus work less like a dSLR and more like a compact camera in that there is no mirror and no optical viewfinder where you can see through the lens.  Instead, there is an LCD on the back of the camera and a digital viewfinder that works like an optical viewfinder on a traditional dSLR except that what you see is a digitized image of what the camera sees through the lens.  In a sense, the Micro Four Thirds system is like a pocket camera with a digital viewfinder that you can put your eye close to in order to see the viewfinder better in bright light.  Having all the features of a dSLR plus the digital viewfinder, it's a compact camera that looks and feels like a dSLR to a large extent.  In the end, whether you call it a dSLR or something else is up to you.  You could argue that point either way, but to me, the most important thing is that the Micro Four Thirds system does make cameras that look, operate, and feel like a dSLR with some useful advantages!

Likely not by accident, the Micro Four Thirds format enabled cameras like the upcoming Panasonic GH1 to have continuous autofocus while shooting video.  Current dSLR cameras such as the Nikon D90 and Canon 5D Mark II cannot (effectively) autofocus during video shooting because their mirrors are flipped up to expose the image sensor and that disables their autofocus systems.  With the Micro Four Thirds cameras like the GH1, the sensor is free to use its contrast detection autofocus in real time just like a consumer camcorder.  Obviously this has its benefits over manual focus in certain conditions.

It may sound like I'm a proponent of the Micro Four Thirds format for use in "new age dSLR" cameras, but it's early in the game and right now I simply find it intriguing.  The multiple mirrors/prisms in traditional dSLR cameras certainly come at a cost and I've always believed they could be removed and benefits realized from a (mechanically) simpler design.  I do get tired of investing in cameras and lenses for traditional dSLR cameras only to find that at least 80% of them have some front/back focus issues in at least part of the zoom range.  In many cases I'm certain about where I focused yet the full size image shows the true focus just in front of or behind where I focused.  I'm looking forward to trying the Micro Four Thirds cameras to see if they put an end to that problem, yet I wonder how well those cameras will handle other aspects like being able to use the digital viewfinder in dim lighting or for fast moving objects, or whether their somewhat smaller sensors can keep up with the "big boys" when it comes to high ISO shooting.  So while I'm optimistic, I think the jury is out but suffice it to say I'll be keeping an eye on this exciting new design for what most of us will still call dSLR cameras. 

Though the Micro Four Thirds format is not limited to dSLR type cameras (it should work well for rangefinder type cameras too), due to the reduced mechanical complexity, Micro Four Thirds dSLR cameras can be as their name suggests: micro!  The camera bodies and lenses for Micro Four Thirds cameras can be made significantly smaller while using image sensors that are only slightly smaller than APS-C sensors used in most traditional dSLR cameras.  The future looks bright for this format so if you are in the market for a compact dSLR camera, keep an eye on the Micro Four Thirds offerings from Panasonic and Olympus.  There are already plenty of selections in the Four Thirds format: it's the "Micro" part that's new!  As of this writing, the only Micro Four Thirds dSLR available in the U.S. is the Panasonic G1 and that doesn't do HD video: you'll have to wait a month or so for the GH1 if you want the first Micro Four Thirds dSLR that can do HD video.

Summary

While I'm hesitant to say that the Olympus/Panasonic Micro Four Thirds format is the next phase in the evolution of the dSLR, the format has some promising advantages that seem to lend the technology to the latest crazes in photography.  Well suited for dSLR video and lending itself to more compact camera/lens sizes, the appeal is certainly there.  Keep an eye on the Micro Four Thirds format cameras and let's see if they can deliver as much in the performance department as they do in functionality.  Only the future and our trusty online reviewers will tell!

Mike Chaney