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Compared to...

We usually select the nearest competition by category, specification, price and feature set for our image quality studio tests. The DP2's decidedly niche design means that it has few obvious peers and the cameras we'll compare it to all have significant differences that need to be borne in mind.

The Olympus E-P1 (along with the Panasonic GF1, which arrived too late for this comparison) is probably the Sigma's closest competitor in terms of specification and intent - it has a very similarly-sized sensor, comparatively compact dimensions and is unashamedly aimed at the photo enthusiast. The significant difference is that the E-P1 is an interchangeable lens camera so, although you can fit a 17mm F2.8 lens that will offer a similar field-of-view and aperture, you can also fit zoom lenses or, as in these test shots - astonishingly sharp specialist lenses.

The Ricoh GR Digital III meanwhile is clearly designed to be another pocket camera for photo enthusiasts. It too has a prime lens, albeit a faster, wider-angle one. In price, as well as concept, the GRD III is not dissimilar to the DP2 however it is built around a much smaller sensor, allowing it to be significantly smaller (it's the only truly pocketable camera here).

The Sony A330 is clearly aimed at a very different market - the first-time DSLR user upgrading from compact cameras and we wouldn't expect anyone to be trying to choose between these two cameras. However, we've used it here to see what the difference in image output is between the DP2 with its comparatively large but unusual sensor and the generic entry-level DSLR that you could buy for a similar amount of money.

Camera Price Sensor
(effective pixels)
Sigma DP2 $ 650 4.69 x 3 MP, 20.7 x 13.8 mm (2.85 cm²)
Olympus E-P1 $ 800 (with 14-42mm lens) 12.3 MP, 18.0 x 13.5 mm, (2.43 cm²)
Ricoh GRD III $ N/A 10.0 MP, 1/1.7" (0.43 cm²)
Sony DSLR A330 $ 550 (With 18-55mm lens) 10.2 MP, 23.5 x 15.7 mm (3.68 cm²)

Lenses used

We tested the Sigma's resolution at various apertures before concluding that F6.3 offered the best balance of sharpness and depth-of-field. The same process was applied to to the GRD III. The Olympus E-P1 was shot using the Four Thirds mount Zuiko Digital 50mm F2.0 on an adapter and the Sony was shot using the Sony 50mm F1.4.

Studio scene comparison (JPEG)

This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F).

Sigma DP2 vs. Olympus E-P1

Camera settings:

  • Sigma DP2: Aperture Priority, ISO 100, JPEG Hi/Fine, Manual WB
    Default Parameters, Landscape mode, Self-Timer
  • Olympus E-P1: Zuiko Digital 50 mm F2.0 Macro lens, Aperture Priority, ISO 100
    JPEG Large/Fine, Manual WB, Default Parameters, Self-Timer
Sigma DP2
Olympus E-P1
2.6 MB JPEG (2640 x 1760)
7.4 MB JPEG (4032 x 3024)

The Sigma's Foveon sensor doesn't require an anti-aliasing filter so, despite its lower resolution, is able to capture incredible levels of detail. However, the average resolution of conventional bayer design sensors has risen to the point that they can record very similar levels of detail (they just need a lot more pixels to do so). The Sigma's color rendition is considerably less convincing than the Olympus, however. Even with a both cameras white balanced to suit the lighting and the Sigma put in 'Landscape' mode to produce slightly punchier colors, the Sigma's output is fairly flat with a distinct green tinge in places.

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