While DSLRs get the lion’s share of the sales for interchangeable lens cameras, mirrorless cameras often get more attention. Maybe it’s their petite size, like the recently shipping Panasonic GM1. Maybe it’s the ability to cram a 36 megapixel full frame sensor into a relatively compact body, as with Sony’s new Alpha 7 series. Pro photographers often use Fuji X-series mirrorless cameras as backups to their normal DSLR rigs. Whether its size, technology or marketing, mirrorless cameras are the hot trend in photography.
DSLRs are bulky, because they require substantial interior space for the flipping mirror and the pentaprism or pentamirror. It’s true that companies have been putting DSLRs on a diet, like Canon’s EOS SL1, but the SL1 is a fairly stripped down, entry level camera. Enthusiast or pro DSLRs tend to be more bulky, like the EOS 6D that Norm’s been using lately. I’ve carried Nikon DSLRs for years, most recently the Nikon D600 full frame DSLR. But I yearned for something more compact and lighter. But I’d become attached to the rich ecosystem of lens possibilities with Nikon’s F-mount.
Of all the mirrorless cameras in the market, one standard stands out as having the most substantial lens ecosystem: Micro Four Thirds. Since both Panasonic and Olympus support Micro Four Thirds, there’s a wide array of lenses available. But what is Micro Four Thirds, and where does it fit into the larger mirrorless camera market?
Four Thirds begets Micro Four Thirds
The original Four Thirds, launched in 2001, created a standard sensor size and aspect ratio. The sensor size is roughly half the area of a typical full-frame DSLR sensor. The aspect ratio of 4:3 (hence “Four Thirds” is similar to some types of medium format cameras and makes printing on standard 8 x 10 photo paper easier. Four Thirds was designed from the ground up to be a purely digital standard.
When Four Thirds launched, a number of companies joined the bandwagon. Olympus and Kodak were the key developers of the standard, but Panasonic and Leica also shipped Four Thirds bodies. These were DSLRs, complete with flipping mirrors and pentaprisms. At the time Four Thirds launched, Olympus viewed the standard as the next generation of professional cameras. Consequently, they developed a rich set of lenses which are still available, some of which are equal to or better than the best Nikon or Canon lenses. Since the sensor offered a 2x crop factor, lenses could be more compact and lighter.
In reality, Four Thirds never really took hold among pro photographers. The biggest guns in the professional camera field, Canon and Nikon, stuck with DSLRs, and relatively few pros picked up on the new standard. Sensor technology was an impediment: a decade ago, small sensors meant poor low-light performance. Olympus made up for this by offering a number of f/2.0 and faster lenses, but these were expensive, and building f/2.0 capable zoom lenses meant that they weren’t as small as they could have been.
In 2008, Panasonic and Olympus developed a new standard, Micro Four Thirds, often abbreviated to Micro 4/3. The sensor size and aspect ratio is the same, but the standard was designed for mirrorless bodies. This allowed the two companies to shrink the bodies even more, but did change the distance from the inner lens surface to the sensor (the flange distance) from the original Four Thirds standard. Micro 4/3 cameras can still use older Four Thirds lenses, but an adapter is needed to extend the length from rear element to the sensor.