The Sigma dp2 Quattro replaces the previous-generation DP2 Merrill, with a radically reworked sensor and strikingly unconventional body. In our Sigma dp2 Quattro review Andy Westlake takes it for a test drive
Sigma dp2 Quattro review – Image Quality
Let’s get one thing absolutely straight: the Quattro’s image quality at low ISO settings is little short of astonishing. Its lens is simply superb, being sharp from corner to corner with no visible chromatic aberration, even when shot at f/2.8. There’s visible (but not objectionable) vignetting when wide open, which disappears by f/4, and a touch of barrel distortion. Overall, this is one of the best optics I’ve ever seen on a fixed-lens camera.The Foveon X3 Quattro image sensor is in its element at ISO 100-400, delivering incredibly sharp, detailed images that look quite unlike files from conventional Bayer-sensor cameras. The pixel-level detail is extraordinary, aided by that wonderful lens, and the sensor is capable of recording subtle changes of colour and tonality from pixel to pixel. So while the sensor’s native output resolution is 19.6 million pixels, it can often match a conventional Bayer sensor with a much higher pixel count for detail.
Image: The dp2 Quattro is capable of outstanding low ISO image quality, thanks to a lens that’s pin-sharp from the centre to the corners
Indeed, to reflect this, JPEG shooters now get the option to output at 39 million pixels, although I’m not convinced there’s much point – they’re just larger files with no more actual detail (and which can’t be shot alongside raw).
The camera’s auto white balance works well, and the JPEG colour output seems richer and more vibrant than from previous Sigma cameras I’ve used, when shot in the default standard mode. A number of alternative colour modes are on offer too, each with fine-tuning of contrast, sharpness and saturation. This means that most users should be able to get images they like straight out of the camera.
Sigma dp2 Quattro review – High ISO performance
Foveon cameras have always been known as being best for low ISO work, something that the Quattro sensor design is supposed to address. In this regard, the camera’s image quality holds up pretty well to ISO 800, although colours can start to smear and desaturate, and shadow detail starts to disappear.
However, at ISO 1600 something very strange occurs to the camera’s JPEG output. The Quattro seems to change its processing mode completely, working at the 4.9-million-pixel resolution of the sensor’s lower layers, then upsampling to 19.6 million pixels. The result is a severe drop in detail, while areas of solid colour can look like they’ve been crudely painted on.
Image: 100% crop from ISO 1600 jpg file from the Sigma dp2 Quattro
Despite this resolution drop, the noise performance still isn’t great, with the Foveon design’s signature green and purple blotching appearing in midtones and shadows. At higher ISO settings, random spots of colour start to appear where the camera misinterprets this noise as real image information, and its noise reduction systems saturate rather than desaturate it.
To get the best high ISO images, it’s therefore imperative to shoot raw. This means processing the resulting images with Sigma Photo Pro 6 – the only program that understands the Quattro’s files.
It’s much, much better at suppressing the sensor’s unusual noise pattern than the camera’s own processing, and can provide reasonable output as high as ISO 3200, although it’s still some way behind cameras that use conventional sensors.
Image: 100% crop from corresponding RAW file converted using Sigma Photo Pro
The price you pay, though, is that Pro Photo is an unintuitive, slow, resource-hungry application that takes an interminable length of time to process raw files, during which you can’t do anything else with the software.