Does Four-Thirds Stand a Chance?

Dan Knight - 2003.05.07

In my previous column, The Digital SLR: Affordable or Overpriced?, we looked at the drawbacks of using 35mm lenses with digital SLRs that have image sensors smaller than a 35mm frame. Dealing with the "conversion factor" is frustrating, and it only seems reasonable that we'll eventually see digital SLRs that take 35mm lenses and produce images from 24 mm by 36 mm imagers.

But Olympus has another idea. Their four-thirds system is designed around a standard sized imager (four-thirds of an inch, hence the name) that will have a sensor measuring about 12 mm by 18 mm. That's half the size of a 35mm frame in each dimension, so each lens for the four-thirds system will be equivalent to a lens of twice the focal length on a 35mm camera (i.e., a 25mm lens on a four-thirds camera will have the same field of view as a 50mm lens on a 35mm camera).

The key to the four-thirds system is standardization. Olympus hopes to create an "open source" camera system that any manufacturer can adopt. Every four-thirds camera will use the same sized sensor and use the same lens mount. Where they go from there will be up to the individual manufacturer.

Picture Olympus producing a digital SLR on a par with the Nikon D100, Fujifilm S2 Pro, or Canon 10D - but significantly smaller, lighter, and less costly. Then picture Minolta, which had very marginal success with their first digital SLR, following suit. Fujifilm is already signed on, and it's quite possible Kodak could participate as well.

With a much smaller imager and smaller lenses, it goes without saying that the cameras needn't be as bulk or heavy as today's digital SLRs designed around modified 35mm SLR bodies. Less material helps reduce the cost, as does using a standard imaging component, which will help make four-thirds competitive.

And all of the cameras don't have to be the same. Olympus might make a traditional SLR style camera with a pentaprism. Maybe Fujifilm will opt for a digital viewfinder instead - no mirror flipping out of the way. It's conceivable that someone who loves the rangefinder style of camera could design a viewfinder camera that used four-thirds lenses along with automatic focus and a nice big LCD on the back of the camera.

A standard sensor size and lens mount will allow manufacturers to identify and fill niches instead of trying to come up with a single model that tries to please everyone. I think it has great potential.

On the other side, lens makers such as Tamron, Sigma, Tokina, Phoenix, and others could make lenses for the four-thirds system, minimizing the need for Olympus and others to bear the cost of producing a full range of lenses. While most camera makers would probably produce a "standard" 15-45mm zoom (equivalent to 30-90mm on a 35mm SLR), perhaps only one would produce a full frame fisheye, only one a 250mm mirror lens, only one a 25mm f/1.0 lens for low light photography.

It's a very different model from what camera manufacturers have traditionally done. Since the demise of the M42 thread mount in the mid-1970s, almost everyone has gone their own way with a lens mount and lens system. (A few did follow the Pentax lead and adopt their K mount, but that was the exception, and even there some companies extended the standard in unique ways that undermined the standard.)

I think there's great potential for companies that are willing to cooperate. If there were a range of four-thirds sensors available from 2 MP to 6 MP, that would be a great start. By swapping that standard component, the same camera could be built for the top or bottom end of the market.

One area where four-thirds will have a benefit over 35mm is lens speed. From a size, weight, and price standpoint, a 28-90 zoom is a wonderful thing. From a low light photography standpoint or shooting range with flash, though, a zoom that ranges from f/4.0 to 5.6 wide open is something of a disaster.

A lot of today's better digicams have zoom lenses a good stop faster than that - and sometimes two stops faster. With the smaller imager and shorter focal lengths, fast lenses need not be large and bulky. Perhaps the "standard" zoom for these would be f/2.8-4.0, giving them an immediate one-stop edge over the larger 35mm cameras.

Of course, it all boils down to price. To find acceptance, four-thirds SLRs would have to be less expensive than today's lowest cost digital SLR, the Canon 10D. It's the only way Olympus and the others can hope to establish a new standard, although there's no reason why more costly models couldn't be produced later on.

There's a window of opportunity here while most digital SLRs are still relatively expensive and don't support the full imaging capabilities of the lenses they use. Once full frame digital SLRs become affordable by the advanced amateur, that window closes. If four-thirds can establish itself before the window closes, the standard could be with us for a good long time. If not, it'll go down in history as another good idea that never quite got off the ground.

Knowing Olympus, I have a strong feeling they'll pull it off. After all, their OM system survived for nearly 30 years despite being launched into a mature, saturated market, and their digital cameras are among the best known in the business.

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