Understanding the Micro Four Thirds System

Reducing the overall size of cameras has been the main driving force behind the new system. This is interesting in the light of the original promise of the Four Thirds System: to produce smaller, lighter cameras, which has thus far been only partially achieved. The new system will offer much of the same functionality as the original Four Thirds system, while allowing camera manufacturers to fit a relatively large image sensor in a very compact camera body.

Front view of the new Panasonic Lumix DMC-G1, which will be released in Australia before Christmas 2008. (The blue version of the camera body is shown.)

The new cameras will support the same three aspect ratios (4:3, 3:2 and 16:9) as Four Thirds system cameras and be compatible with existing Four Thirds system lenses (although only via an adaptor). However, lenses designed for the new system can’t be used on Four Thirds system bodies. Live View shooting capabilities will be provided in all MFT cameras.

According to press releases from both companies, the distinguishing characteristics of the Micro Four Thirds System standard are:

1. The flangeback distance (mount-to-sensor distance) is approximately 50% shorter;
2. The outer diameter of the lens mount is 6mm smaller;
3. The number of electrical contacts in the lens mount has been increased from 9 to 11.

It may not look like a huge difference but these physical changes have significant consequences because the lenses can be made smaller and lighter than Four Thirds system lenses. Potential exists for manufacturers to develop lenses as small as those for rangefinder cameras – and with similar apertures and focal lengths.

Interestingly, it’s currently unclear as to whether independent lens manufacturers like Sigma and Leica would be able to develop lenses for the new system. However, it’s certainly possible as it’s easier to manufacture telecentric lenses (an optical design in which imaging rays remain as close as possible to parallel as they pass through optical system) with small back-focal distances. In addition, the LiveMOS chips used in most Four Thirds DSLRs aren’t as severely affected by angled light as CCD sensors. These factors could make cameras and lenses cheaper to produce.

Increasing the number of electrical contacts in the lens mount will also allow the camera manufacturers to add new features and increased system functionality in the future. No details have been released as to what these ‘new features’ will be but it’s reasonable to think video capture will be an early addition.

Enthusiast Appeal?
We believe the success of the new format will be dictated mainly by its appeal to enthusiast and professional photographers, many of whom are hanging out for a sophisticated, high-quality camera that’s small enough to be pocketable. Point-and-shoot photographers are unlikely to forsake existing digicams for more expensive MFT system models, largely because they don’t want the hassle of carrying and changing lenses.

Whether MFT system cameras will appeal to photo enthusiasts will depend on how camera manufacturers implement the system. Initial product information released by Olympus and Panasonic suggest they are taking radically different approaches. Panasonic will be first to bring products to the market, with its G1 plus two compatible lenses scheduled for local release in November.

Styled like a digital SLR and measuring 124 x 83.6 x 45.2 mm with a body weight of approximately 385 grams, the 12.1-megapixel (effective) G1 isn’t much smaller than the Olympus E-420 (which at 129.5 x 91 x 53 mm was previously the smallest interchangeable-lens camera) but is five grams heavier. Providing all the controls and shooting modes you would expect on an enthusiast’s camera, the G1 will be offered in black, blue and red and supports two levels of JPEG compression and simultaneous RAW+JPEG recording. Image data is recorded to SD/SDHC memory cards.  

Back view of the red version of the Panasonic Lumix DMC-G1, showing the adjustable LCD panel in the closed position.

Olympus has shown a “concept mock-up” at Photokina 2008 that looks more like a compact digicam than an enthusiast model. No technical specifications have been released thus far, although pictures of the concept model have been released. As to when it will reach the market, Olympus has stated in a press release, “the product name, launch date and retail price of the first Olympus interchangeable lens type digital camera based on the MFT System will be announced in the future”.

Front and rear views of the concept Micro Four Thirds camera shown by Olympus at Photokina 2008 in September.

Many photo enthusiasts are looking for a compact camera with a large sensor and full suite of adjustable controls (think of a Canon G10 or Panasonic LX3 with an 18 x 13.5 mm or larger imaging chip). If either company can deliver such a camera, they could be onto a winner – particularly if it can accept proportionately-small interchangeable lenses. However, the arguments are much less persuasive for buying a camera that is as heavy and bulky as existing DSLRs.

Mirrorless Advantages and Disadvantages
Many benefits can be delivered by eliminating the reflex mirror system. As well as allowing the rear lens element to be closer to the sensor, which supports more compact lens designs, other advantages include:
1. 100% accurate framing because an EVF can display exactly the same image as the sensor records. In contrast, the viewfinders in most DSLRs provide around 95% coverage of the sensor’s field of view, making precise and accurate framing difficult.

2. No mirror slap to blur close-up or long telephoto shots. (This alone will provide up to a stop of shutter speed advantage for hand-held shooting – without requiring additional stabilisation.)

3. If you wish to shoot in monochrome (B&W, sepia or any other colour), the EVF allows you to see and compose the shot as it will be captured.

4. Accurate depth-of-field preview without the need for a DOF preview button because EVFs display the exact DOF for the selected f-stop.

5. Instant zoom in for focus checking without the need for a focus magnifier.

6. On-demand grid lines, framing guides, centered crosshairs, etc. You can even display a histogram on the screen – or an ‘artificial horizon’ levelling aid. If that’s too much on-screen information, you can also switch to an uncluttered view – quickly and easily.

7. A bright display in dim lighting. It’s easy to boost the brightness of an EVF, making it usable in near-dark conditions. The same facilities aren’t available with optical finders.

8. No added rectilinear distortion due to the focusing screen condenser lens.

On the other hand, there are some disadvantages in going mirrorless. For starters, most current EVFs provide relatively poor viewing quality. Radical improvements will be required to make EVFs satisfactory for current DSLR photographers (the technology is well overdue for a significant upgrade).

Then there are challenges associated with autofocus and exposure mechanisms, both of which rely on the reflex mirror system for their speed and accuracy. There’s a possibility MFT cameras will show the same capture lag as a typical digicam – which will frustrate ebthusiast users.

Where to Four Thirds?
While the original Four Thirds system was established as an open system to encourage other manufacturers to support it, so far only two companies have actually produced cameras for the format. Fujifilm and Kodak, both of which expressed initial support, remain without products in the marketplace and no apparent interest in producing any.

Olympus currently has the strongest commitment to the Four Thirds system, having developed the first cameras to go on sale and following the initial E-1 with nine other models, along with more than 20 lenses (three of which have been discontinued). The company has also announced the development of a tenth E-series DSLR, which will be positioned between the E-520 and E-3 and is due to launch in the first quarter of 2009.

Sigma has also shown a strong commitment having produced 13 Four Thirds system lenses to date (of which two have been discontinued). Panasonic has only four lenses and two camera bodies thus far. Leica has the Digilux 3 (effectively a rebadged Panasonic DMC-L1). Currently, 34 Four Thirds system lenses are available, along with two teleconverters an extension tube and an adapter mount.

Although both Olympus and Panasonic have stated their on-going support for the Four Thirds format, we can’t help seeing the move to a smaller, more compact form factor as anything other than a recognition that the original system has not lived up to its promises. When competing against cameras with ‘APS-C-sized’ sensors from all the other DSLR manufacturers, the smaller sensors in Four Thirds system cameras put then at a disadvantage.

You can’t deny the laws of physics: larger sensors can have larger photosites and larger photosites can collect more photons with less background noise. No amount of processing can produce images that are as clean and sharp as those captured with minimal noise levels because processing has a tendency to soften images as part of the noise-reduction process.

But if the new cameras stick with 10-megapixel or lower resolution, they could command a valuable market niche. For most photographers, particularly those who never make prints larger than A4 size, 10-megapixel resolution is more than enough.