Sigma DP2 Quattro
Sigma’s cameras have been designed for imaging geeks ““ and will only suit photographers who are prepared to shoot and work with X3F.RAW files.
No other sensor can match the output from the latest Foveon chip, which is noticeably superior to the sensors in the DP Merrill series of cameras that pre-date the Quattro models.
Like the Merrill models, the DP2 Quattro performs best at low ISO settings (ISO 400 the absolute maximum) and is best suited to photographing static subjects. It’s possible to take pictures of moving subjects and even hand-hold the camera with quite slow shutter speed but for optimal results, tripod mounting is recommended.
However, many of the limitations in the previous models carry over into the new camera.
We’ve held an on-going admiration for Sigma’s cameras and lenses and, specifically, for the rich colours produced by the Foveon sensors used in all Sigma cameras. February saw the launch of a new trio of fixed-lens compact cameras under the ‘Quattro’ brand name which introduced an updated sensor and a radical re-design for the camera bodies. The DP2 is the first camera in the new Quattro series to be released, with a DP1 and DP3 Quattro to follow.
Angled front view of the DP2 Quattro. (Source: Sigma.)
Like its predecessors, the DP2 Quattro has a fixed lens and non-adjustable LCD monitor. It lacks both viewfinder and built-in flash, although both can be added optionally via a hot-shoe on the top panel. Only four shooting modes are supported: Program AE (with Program Shift), Shutter Priority AE, Aperture Priority AE and Manual exposure. You can’t record movies at all.
Who’s it For?
Sigma’s cameras have been designed for imaging geeks ““ and will only suit photographers who are prepared to shoot and work with X3F.RAW files. No other sensor can match the output from the latest Foveon chip, which is noticeably superior to the sensors in the DP Merrill series of cameras that pre-date the Quattro models.
Like the Merrill models, the DP2 Quattro performs best at low ISO settings (ISO 400 the absolute maximum) and is best suited to photographing static subjects. It’s possible to take pictures of moving subjects and even hand-hold the camera with quite slow shutter speeds but for optimal results, tripod mounting is recommended.
However, many of the limitations in the previous models carry over into the new camera. These will presents obstacles potential purchasers should be aware of:
1. The lack of a viewfinder means you’re forced into point-and-guess shooting in bright outdoor situations. Even with the monitor’s brightness racked up as far as it can go, we found it impossible to see enough detail in scenes to compose shots with any degree of precision. In addition, the screen refresh rate is relatively slow.
2. Photographers planning to use this camera for landscape photography should invest in the optional VF-41 compact optical viewfinder (RRP AU$249), which matches the angle of view of the 30mm lens. No EVF is available.
3. No lens hood is supplied with the camera and there’s no built-in flash.
4. There are no scene pre-sets or in-camera special effects and no stabilisation.
5. Power consumption is relatively heavy and users will need to keep the spare battery charged and ready to use on even relatively brief shoots.
6. There’s no movie mode.
7. You have to use Sigma’s raw file processor to convert the X3F.RAW files into editable formats. (It’s available as a free download from Sigma’s website.) It’s pretty quirky and adds extra steps to your normal workflow.
8. The buffer limit of seven JPEGs or 3.7 raw files restricts continuous shooting options and writing speeds are sluggish, even with fast memory cards.
As for previous models, the DP2 Quattro is supplied with two rechargeable batteries to compensate for the relatively low (200 shots/charge) power efficiency of the camera.
Aside from the new sensor, which is covered separately below, the main feature that draws attention to the DP2 Quattro is its unusual body design. At 161.4 mm, the camera body is very long for a fixed-lens camera and it has a large and unusually-shaped grip on the right hand end.
There are two reasons for this: the camera’s image processor requires more power than previous models and a larger surface area is required to dissipate the heat it generated. The camera body becomes quite warm with use.
Front view of the DP2 Quattro. (Source: Sigma.)
The front of the camera turns outwards through roughly 20 degrees then swings back through 90 degrees to form a boxy projection where the battery is housed. A small rubberised pad is located in this area for a finger rest. We’re not overly enamoured of the new design but have become accustomed to it with use.
Ergonomically, the DP2 Quattro isn’t the most comfortable camera we’ve used. The length of the camera body and its control layout make it more suitable to two-handed shooting, although the shutter can be triggered when the camera is held in one hand. But it’s vulnerable to camera shake (and there’s no stabilisation). One-handed use works better when the camera is held vertically in portrait orientation.
The lens covers roughly a third of the front panel and extends slightly above the top of the main body. A welcome feature is the manual focusing ring on the lens barrel, which allows precise adjustments to be made. Dual microphone holes are located in the short section to its left. An AF-Assist LED is located inside the lens barrel.
Top view of the DP2 Quattro. (Source: Sigma.)
After about 40 mm the grip section curves back parallel to the rear panel and then slopes inwards. The shutter button is located in this section of the top panel, surrounded by the front control dial. The second dial sits behind it, offset towards the rear right hand corner. This ‘box’ provides a grip area large enough to satisfy users with large hands (but probably daunting for those with small ones or short fingers).
The only other controls on the top panel are the power switch and mode button, which lie between the hot-shoe and the shutter button assembly. The hot-shoe is designed for the optional EF-140S SA-STTL flashgun, which has a GN of 14 (ISO 100/m). There’s no built-in flash.
A rubberised coating on the rear panel between the monitor and the edge of the grip ‘box’ provides a reasonably secure thumb rest. Located on the rear of the grip ‘box’ adjacent to the end of this coating is the arrow pad (‘selector’), which carries a prominent ‘FOCUS’ label and AF point selector icon.
Rear view of the DP2 Quattro. (Source: Sigma.)
Much of the rear panel is dominated by the 3.0-inch, 920,000-dot LCD monitor, which is almost flush with the rest of the panel. It’s better than the previous model’s but remains difficult to ‘read’ in bright outdoor lighting. Four buttons ““ Display mode, Quick Set, AE-lock / Delete, and Menu ““ line up near its right hand side, with a play button sandwiched between the Menu button and the edge of the monitor.
The memory card slot is located on the left hand side panel beneath a rubber cover that also protects the USB port in the same compartment. The battery compartment is in the standard position on the base plate, below the grip box. Its cover has DC connector cut-out that can be removed to allow the camera to be powered from the mains. Two ridged rubber pads on the base plate add a small amount of padding, particularly around the tripod mount, which is metal-lined and located on the lens axis.
Sensor and Image Processing
The new Foveon X3 Quattro sensor is a development of the chip in the three Merrill cameras. It still uses separate layers for recording red, green and blue wavelengths, eliminating the need for a low-pass filter.
Some changes have been made to address issues associated with earlier chips, notably cross-contamination of colours between channels, increased noise and reduced saturation at sensitivities higher than about ISO 400 and reductions in image dynamic range. Previous sensors have also been hampered by relatively slow processing times.
The diagram above shows how resolution and colour information are recorded by the new Foveon X3 Quattro sensor. (Source: Sigma.)
The new sensor’s top layer captures luminance (greyscale) and blue colour information (which underpin resolution), while the layers below record colour information only for the green and red bands. The photodiodes are distributed in a 1:1:4 ratio, with the top layer containing 19.6 million photodiodes, leaving each of the lower layers with 4.9 million photodiodes.
The Foveon design has the advantage of greater symmetry than designs using Bayer filtration. But it relies on having the upper and lower layers in perfect alignment and depends upon the strength of the signal and the signal-to-noise ratio that can be extracted from the sensor. This could partly explain the relatively small range of sensitivities the sensor can support.
It’s always been difficult explaining the actual resolution of Foveon sensors because Sigma tends to claim the highest figures it can by combining the three layers. In the past, we have relied on Imatest, which effectively divides the total number of photosites by three. But since the top layer determines the resolution, Imatest now shows this chip as having 19.6 megapixels. This is the figure we will use when evaluating the camera’s performance.
When the image data is processed by the updated TRUE III image processor, the luminance data information captured in the top layer is applied to the top, middle, and bottom layers, resulting in luminance and colour data for each individual pixel. The result is shown in the diagram below.
Combining resolution and colour information. (Source: Sigma.)
Sigma claims the new structure is designed to prevent ‘file bloat’, which was a risk with previous sensors that contained RGB information for every pixel location. However, it could also increase the risk of colour moirø© and false colour artefacts, which previous sensors have avoided.
On the positive side, processing speeds should be faster because there’s less data to ‘read’ from the sensor and process. However, the actual gains are barely detectable, when compared with the equivalent Merrill model. Noise, particularly in the green and red channels, should also be reduced because larger photodiodes are used in these layers. (We found this to be the case, although high ISO images are still relatively noisy.)
The new TRUE (Three-layer Responsive Ultimate Engine) III processor has been developed especially for the new-generation sensor and offers 14-bit processing. The DP2 Quattro offers two images sizes for X3F.RAW files, which are recorded with a 3:2 aspect ratio. Five aspect ratios are available when recording JPEG files: 21:9, 16:9, 3:2, 4:3 and 1:1. Three image sizes are available for each: Super-High, High and Low.
Movie recording isn’t supported.
The lens on the DP2 Quattro has the same specifications as in the DP2 Merrill’s lens but is optimised to match the new Foveon X3 Quattro sensor. Sigma has placed a priority on transmitting light wave information directly to the sensor while minimising ‘every type of optical aberration’.
The optical design of the DP2 Quattro’s lens, with the aspherical element shown in purple. (Source: Sigma)
The optical design comprises eight elements in six groups, with one aspherical element, as shown in the diagram above. This lens has an aperture range of f/2.8 to f/16 plus a nine-bladed iris diaphragm. It can focus to 28 cm with a maximum magnification of 1:7.6 and is threaded to accept 58 mm filters.
Although the supplied camera had the original firmware and an updated version (1.0.2) was released during our testing period we chose not to install it because we suspect the cameras in local stored haven’t been updated. The new firmware is available for downloading at http://www.sigma-global.com/en/download/cameras/firmware/.
As far as we’ve been able to determine, the update addresses issues associated with the rendering of certain colours, particularly reds and magentas. Corrections were also provided for magenta and green tints appearing in neutral-toned areas. We didn’t notice any of these issues in test shots, including X3F.RAW files converted with Sigma Photo Pro 6.
Images from the review camera were every bit as good as we expected, based on having reviewed the DP2 Merrill in September 2013. Imaging performance at higher ISO settings was better than we found with the DP2 Merrill but ISO settings above 1600 are still best avoided if you don’t want visible noise.
No moirø© was visible in any of our test shots, suggesting this may not be an issue. Subjective assessments of JPEG originals showed them to be sharp and detailed, although colour rendition wasn’t nearly as with rich and vibrant as we obtained with the DP2 Merrill.
Raw files were converted into TIFF format with Sigma Photo Pro 6 without additional processing produced images that were remarkably similar to JPEGs straight from the camera. This may explain the interesting results we had with our Imatest tests, which showed JPEG files to have higher resolution than X3F.RAW files at ISO settings up to 800, where they were roughly equal.
After that, the TIFF files from the raw files contained much higher resolution than their equivalent JPEGs, which showed little change as sensitivity increased. The graph below shows the results of our tests.
As before, Imatest showed the 30mm lens to be a superior performer, which maintained high resolution for both centre and edges of the field of view from f/2.8 to f/8, where diffraction began to take effect. Slight edge softening was detected at apertures up to f/4, as shown in the graph of our test results below.
Lateral chromatic aberration was negligible at all aperture settings, as shown in the graph below, in which the red line indicated the border between ‘negligible’ and ‘low’ CA. Very little coloured fringing was seen in test shots.
The lens showed some tendency to flare in strongly backlit situations where a bright light source was included in the image frame. Normal backlit subjects showed no signs of flare and retained their full dynamic range and vibrant colours.
Long exposures at night had plenty of colour and clarity, with slight softening becoming just detectable at ISO 800. But image noise only became really noticeable at ISO 6400, and even then, files were printable at snapshot size. This is a significant improvement over the DP2 Merrill, where noise became noticeable at ISO 1600 and very obvious at ISO 3200.
Auto white balance performance was relatively good. A slight residual orange cast remained in shots taken under incandescent lighting. But fluorescent lighting delivered shots with close-to-neutral colours and the pre-sets delivered acceptable corrections for both colour casts without going overboard.
Our timing tests were conducted with an 8GB SanDisk Extreme Pro SDHC UHS-1card. The review camera took 1.9 seconds to power up ready for shooting. We measured an average capture lag of 0.3 seconds which was eliminated with pre-focusing, indicating a reduced AF lag compared with the DP2 Merrill. In low light levels it still could still take a second or two to find focus.
Processing times are much faster with the new camera. It took 4.8 seconds, on average, to process one high-resolution JPEG file; 9.4 seconds for each X3F.RAW file and 10.2 seconds for each RAW+JPEG pair. Shot-to-shot times averaged 1.9 seconds for both JPEGs and raw files.
In the continuous shooting mode the review camera recorded seven Large/Fine JPEGs in 1.8 seconds, which is marginally slower than the DP2 Merrill’s burst rate. It took well over 30 seconds to process this burst.
The buffer limit remained at seven frames for both files and RAW+JPEG pairs and capture rates remained constant. However, processing times were extended to 48.8 seconds for raw files and 50.9 seconds for RAW+JPEG pairs.
Sigma’s cameras won’t suit snapshooters and many basic photo enthusiasts will find them difficult to accept, given their very extensive limitations. The DP2 Quattro is very much a niche camera ““ that operates in a rather small niche. And its price tag is relatively high for what you get, particularly when compared with previous DP cameras, which is why we haven’t given it an Editor’s Choice award.
The DP2 Quattro provides only a few advantages over its ‘Merrill’ branded cousin, which is currently selling for roughly half the price of the Quattro. Most noteworthy are better performance at mid-to-high ISO settings and slightly faster response and processing times. However, its more subdued colour reproduction will probably disappoint some potential purchasers.
Although more sprightly than the Merrill alternative, the new camera remains fairly ponderous to use and the software (which is required for processing raw files), though capable, is still quirky. If you want detail that rivals the best DSLRs we’ve reviewed, Sigma cameras are hard to beat, but we think the Merrill alternative adequately satisfies this requirement.
Image sensor: 23.5 x 15.7mm Foveon X3 Direct Image Sensor (CMOS) with approx. 33 million photo detectors [T(Top): 5424 x 3616/ M(Middle): 2712 x 1808/ B(Bottom): 2712 x 1808], approx. 29 megapixels effective
Image processor: TRUE III Image Processing Engine
A/D processing: 14-bit
Lens: Fixed 30mm f/2.8 lens (approx. 45mm equivalent in 35mm format); 8 elements in 6 groups; 58 mm filter thread
Image formats: Stills ““ X3F.RAW, JPEG (Exif V. 2.3), RAW+JPEG
Image Sizes: Stills ““ RAW: 5424 x 3616, 2712 x 1808; JPEG: 21:9 aspect: 7680 x 3296, 5424 x 2328, 2704 x 1160; 16:9 aspect: 7680 x 4320, 5424 x 3048, 2704 x 1520; 3:2 aspect: 7680 x 5120, 5424 x 3616, 2704 x 1808; 4:3 aspect: 6816 x 5120, 4816 x 3616, 2400 x 1808; 1:1 aspect: 5120 x 5120, 3616 x 3613, 1808 x 1808
Image Stabilisation: No
Shutter speed range: 1/2000 second to 30 seconds
Exposure Compensation: +/- 3EV in 1/3EV increments
Exposure bracketing: +/- 3EV in 1/3EV steps
Other bracketing options: No
Self-timer: 2 or 10 seconds delay
Focus system: 9-point contrast detection type with Free move mode and three Focus Frame sizes: Spot, Regular and Large. Range: 28 cm to infinity; AF-assist LED
Focus modes: Face Detection AF, manual focusing via ring on lens, LIMIT Mode (for Macro, Portrait and Scenery)
Exposure metering: Evaluative, centre-weighted average and spot metering
Shooting modes: Program AE (Program Shift is possible), Shutter Speed Priority AE, Aperture Priority AE, Manual exposure
Colour Modes: Standard, Vivid, Neutral, Portrait, Landscape, Cinema, Sunset Red, Forest Green, FOV Classic Blue, FOV Classic Yellow, Monochrome; contrast, sharpness and saturation adjustable for each mode; monochrome images can have red, green, blue, yellow or orange filter effects or red, warm tone, sepia, green, blue green, blue, cold tone, blue purple or purple toning applied
ISO range: Auto,ISO 100 to ISO 6400 in 1/3EV steps(high limit, low limit setting is possible)
White balance: Auto, Auto (Lighting Source Priority), Daylight, Shade, Overcast, Incandescent, Fluorescent, Colour Temperature, Flash, Custom
Colour space: sRGB and Adobe RGB
Flash: No (hot-shoe provided for external flashguns)
Sequence shooting: Max. approx. 7 shots/sec. at High resolution (14 frames at low resolution)
Buffer memory depth: 7 JPEGs, 7 raw files, 5 RAW+JPEG
Storage Media: Single slot for Memory Stick PRO Duo or SD/SDHC/SDXC memory cards; UHS-1 compliant
Viewfinder: No (optional external OVF available)
LCD monitor: Fixed 3-inch TFT LCD with approx. 920,000 dots
Other features: Grid overlay with 4, 9, 16 segments in white or black, electronic level, dial customisation, Eco mode, camera sound adjustment
Playback functions: Single image, zoomed-in view (up to 10x magnification available), 9-frame index view, image + basic shooting data, image + detailed shooting data and RGB plus brightness histograms, delete single/marked/all images, lock single/marked/all images, rotate images, exposure warning display, slideshow playback with adjustable durations, DPOF support
Interface terminals: USB 2.0, cable release switch
Power supply: BP-51 rechargeable lithium-ion battery; CIPA rated for approx. 200 shots/charge
Dimensions (wxhxd): Approx. 161.4 x 67 x 81.6 mm
Weight: Approx. 410 grams ( without battery and card)
Based upon JPEG files.
Based upon X3F.RAW files converted into TIFF format with Sigma Photo Pro 6.
Auto white balance with incandescent lighting.
Auto white balance with fluorescent lighting.
30-second exposure at ISO 100, f/5.6.
8-second exposure at ISO 400, f/4.
4-second exposure at ISO 1600, f/6.3.
2-second exposure at ISO 3200, f/5.6.
2-second exposure at ISO 6400, f/8.
Fine details recorded in a close-up shot with the Macro AF setting. ISO 100,1/250 second at f/7.1.
Strong backlighting with slight flare. ISO 100, 1/250 second at f/6.3.
Average backlighting. ISO 100,1/200 second at f/5.6.
ISO 160, 1/400 second at f/8.
Crop from the above image showing the typical extent of coloured fringing.
ISO 100,1/250 second at f/11.
ISO 100, 1/160 second at f/8.
Vivid colour mode; ISO 100, 1/400 second at f/7.1.
Monochrome mode; ISO 200, 1 /125 second at f/5.
ISO 100, 1/400 second at f/8.
ISO 400, 1/80 second at f/3.5.
Mixed indoor lighting; ISO 500, 1/30 second at f/4.
Indoor lighting; ISO 400, 1/8 second at f/2.8. Hand held.
RRP: AU$1049; US$1400 (discounted to $999)
- Build: 9.0
- Ergonomics: 7.5
- Autofocusing: 8.0
- Still image quality JPEG: 9.0
- Still image quality RAW: 9.0