The different types of DSLR formats

Here is an interesting article by www.photoreporter.com that summarizes the differnces in digital camera formats between the different manufacturers. The formats includes Full Frame 24 x 36mm, Four Thirds 17.3 x 13mm and the common APS-C 22 x15mm.

Here's what they say about each format.

Full-Frame Format

The full-frame digital format was pioneered by Canon in the EOS-1D of 2002, and they’ve been using it for all their EOS-1–series professional DSLRs, including the current top-of-the-line EOS-1Ds Mark II and, more recently, the extremely successful prosumer EOS 5D. Essentially what makes it possible is Canon’s CMOS sensor technology—a 24x36mm CCD would still be prohibitively expensive at this point, and that’s the main reason why only Kodak and, very briefly, Contax, were the only other companies to field DSLRs using this format.

The advantages of full-frame digital sensors include:

1. The ability to use 35mm SLR lenses, particularly wide angles and ultra wides, without curtailing their angle of view. It does however exposes poor quality optics.

2. Better ability to control depth of field with aperture selection.

3. Larger pixels able to capture more color information and deliver better imaging performance at high ISOs and thus producing less noise. This is more so in low light situations.

The downsides of full-frame DSLRs can be stated as: They tend to be larger, heavier and more expensive than models with smaller sensors. And their lenses have to be larger and heavier as well to cover the larger, oblong 24x36mm format, which doesn’t match standard enlargement sizes like 8x10 and 16x20. Clearly a full-frame DSLR makes a lot of sense for a pro or anyone else with a big investment in wide- and ultra-wide-angle 35mm lenses, and few will quibble with the outstanding image quality provided by the Canon DSLR models cited above.

The question raised by the introduction of the red-hot Canon EOS 5D is therefore not so much a technical question as a marketing question: namely, will Canon or anyone else bring out a consumer full-frame DSLR for, say, $1,000 and blow everything else into the weeds? Answer: Not bloody likely. Canon, in the interest of profitability, seems determined to maintain a two-format policy, remaining steadfastly committed to APS-C–format DSLRs like the new prosumer EOS 30D and the consumer/mass market EOS Rebel XT on the one hand, and the full-frame EOS-1 series and 5D on the other. The twain will not meet in the foreseeable future, and prices for full-format DSLRs will be maintained at the $2,000+ level going forward.





Four Thirds Format

When Olympus unveiled the Olympus E-1 on June 24, 2003, they extolled it as the first DSLR system designed for digital from the ground up. Using a 4/3-type CCD sensor measuring 17.3x13mm with a diagonal of 22.5mm, its aspect ratio is 4:3 (hence Four Thirds,) with a lens mount twice the diameter of the image circle of the lens.

The system is claimed to provide less fall off and superior image quality, especially with wide-angle lenses, by allowing the incoming light to strike the sensor directly rather than at oblique angles. Other advantages of the FT system are: 1. Improved optical efficiency due to a less-oblong format requiring a smaller image circle. 2. Smaller, lighter, easier-to-design lenses, and potentially smaller, lighter camera bodies. 3. The format enlarges directly to popular enlargement sizes like 8x10 and 16x20 with no wasted image area.

While the pro-aimed Olympus E-1 had a tough time going up against such well-entrenched competitors as Nikon and Canon, the FT system has really come into its own with successful consumer DSLR models like the Olympus EVOLT E-300 and the new EVOLT E-330. And the FT system clearly received its biggest shot in the arm yet at PMA 2006 with the announcement of cooperation between Olympus and consumer electronics giant Panasonic, the introduction of Panasonic’s high-end Lumix DMC-L1 using the FT system and a new Leica FT-mount lens, and Sigma’s adding of five new FT-system lenses to the existing line of Olympus and Sigma FT-mount optics.

To say that advocates of the Four Thirds system are ecstatic about these recent developments is an understatement. Many claim that Panasonic and Olympus are now poised to capture a significant market share. Most skeptics acknowledge that the FT system is technically viable, but they question whether those still in the process of moving from 35mm to DSLRs can be persuaded to switch to the FT mount, and whether sufficient numbers of new consumer DSLR buyers will go for an alternative to the still-dominant APS-C format. However, with the marketing and technical prowess of Panasonic behind it, the FT format stands a good chance of success, particularly if Olympus and Panasonic continue to introduce attractive, stylish and compact new DSLR cameras and lenses at competitive price points.





APS-C Format

APS-C is the format that really ignited the DSLR revolution, beginning with pro-aimed models from Nikon and Canon. Eventually, as prices came down and the market broadened, enthusiast and consumer models were offered by every major SLR maker, notably Pentax and Konica Minolta, and now Samsung and Sony. With a 2:3 aspect ratio like 35mm, APS-C enabled 35mm SLR owners to make a reasonably seamless transition to digital, and as the top models from Nikon, Canon and Pentax prove, this format is certainly capable of delivering professional quality images.

Actually APS-C is only a nominal format designation. Most DSLRs using it have CCD or CMOS sensors measuring 22.5x15mm, giving a multiplication factor of 1.6 when calculating 35mm-equivalent focal lengths. Nikon uses the DX system with slightly larger CCD sensors measuring 23.6x15.8mm, which works out to a multiplication factor of 1.5.

Telephoto fans are thrilled with APS-C because their tele lenses are “longer” thanks to the “cropping factor,” but wide-angle fans generally have to buy new wide-angle lenses and wide zooms specifically designed for APS-C–format cameras. Lens makers have been very happy to oblige, creating many outstanding new lenses that will only work on APS-C DSLRs. And while APS-C does not enlarge directly to 8x10 without cropping, it sure provides full-frame 4x6s that are vastly more popular among amateurs.

With a continuing strong commitment from the likes of Canon, Nikon, Pentax and Sony, APS-C in its slight variations certainly seems destined to be the dominant DSLR format for years to come. Though it is possible that full-frame DSLRs at one end and FT-format cameras on the other will nibble at its market share. But unless something dramatic and unexpected happens, like an entirely new DSLR form factor or a radical world-beating design, it sure looks like all three formats will be around for years to come. I’m not normally a wagering man, but I’d bet on it.




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