- Foveon sensor with excellent pixel level detail
- Solid and well built camera body
- Sub display screen
- Large electronic viewfinder
- Dual axis electronic level
- Good value for money
- Easy to access controls
- Raw processing required to correct for CA
- Sigma Photo Pro is slow (but better than older versions)
- Slow refresh in EVF / Screen
- Lacks video recording
- No Wi-Fi built-in (but Eye-Fi compatible)
- Super Fine Detail slow and memory intensive
- Slow focus speeds
The Sigma sd Quattro is the new mirrorless interchangeable lens camera from Sigma, and replaces the SD1 Merrill, which was Sigma’s Digital SLR camera. The sd Quattro features the same Sigma SA lens mount, making it compatible with all Sigma SA lenses. The sq Quattro features the same APS-C Foveon sensor as the dp Quattro series, and is available for £799/$1,198 body only, or £999/$1,498 with 30mm f/1.4 Art lens.
The core of Sigma cameras is the Foveon sensor, something that is unique to Sigma, with no other manufacturer featuring a Foveon sensor. The Sigma sd Quattro uses the newly developed Foveon X3 direct image sensor (generation name: “Quattro”), as featured in the dp Quattro series.
The Foveon sensor features multiple layers to capture all of the colour information that visible light transmits, much like 35mm film, so that every pixel position on the sensor captures red, green and blue, compared to a normal sensor, which captures a single colour at each pixel, as shown below.
The Foveon X3 Quattro direct image sensor differs from the previous Foveon sensor thanks to a new top layer with a higher 19 megapixel resolution, as shown below. This is said to give high resolution results, but with a lower resolution 4.9 megapixel green and red layer, that means image processing is said to be quicker and noise is also said to be improved.
Sigma dp Quattro Sensor design (Image courtesy: Sigma)
Due to the sensor design, there is no low pass filter, and each pixel records full RGB colour information, thanks to a layered sensor, much like film. The previous Sigma dp Merrill series was said to give the equivalent of a 30 megapixel camera from a 15mp (x3) sensor, while the dp Quattro series is said to give the equivalent of a 39 megapixel camera when compared to a Bayer sensor camera, thanks to the 29.8 megapixel sensor (20mp + 4.9mp + 4.9mp), and full colour information for each pixel.
When Sigma introduced the sd Quattro, they also announced the sd Quattro H, which features a larger, higher resolution sensor, and we’ve run through the main differences between the two cameras below:
|Sigma sd Quattro||Sigma sd Quattro H|
|29.8 megapixel APS-C (23.4×15.5mm)||38.6 megapixel APS-H (26.7×17.9mm)|
|1.5x crop factor||1.3x crop factor|
|1.1x viewfinder magnification||0.96x viewfinder magnification|
|625g weight||630g weight|
Sigma has added a new mode called “Super Fine Detail” – this mode takes a number of pictures, in a unique Sigma raw file format, and then you need to process this image to export it as a JPEG or the normal Sigma raw file. The mode is takes 7 shots for improved dynamic range with low noise. You can’t view the result in camera, and the file is recorded with a .X3I extension. As the camera is taking a number of shots, a tripod is necessary.
The rear of the camera features a 3inch screen, plus a secondary LCD display with camera settings displayed. There is a high resolution 2.36m dot electronic viewfinder (EVF) with dioptre adjustment, and 1.1x magnification. The camera has the usual P, A, S, and M shooting modes, plus 3 custom shooting modes. The camera does not feature built-in Wi-Fi nor a video mode.
An optional battery grip, called the Power Grip PG-41 is available. The camera supports tethering with “Sigma Capture Pro” so that you can control the camera from your computer and shoot remotely, for example in a studio setup.
A unique feature of the SD1 / Merrill series was the ability to remove the infrared filter from the camera, and this continues with the sd Quattro, meaning it’s quick and easy to remove the filter, and use the sq Quattro for infrared photography (with the correct infrared filter to block visible light).
- 33 / 29.8 megapixel total pixels (19.6 megapixel top layer), 39 megapixel max image size
- APS-C Foveon sensor (23.5×15.5mm), 1.5x crop
- 3.6fps – up to 14 continuous shots, 5.1fps with Low image size (28 images)
- Sigma SA lens mount
- Dual TRUE III image processor
- New Super Fine Detail exposure mode
- Combination of Phase detection AF and contrast detection AF
- Focus peaking function, Quick set menu
- 2.36m dot electronic viewfinder (EVF), 1.10x magnification
- 3.0inch 1.62m dot screen
- Magnesium alloy body, with dust and splashproof design
- 14-bit RAW data, In-camera RAW processing
- Higher precision white balance (new algorithm)
- Colour modes, Monochrome options
- Custom bracketing display
- Electronic level
- USB3 port
The sd Quattro is a fairly large mirrorless camera, with modern styling that makes it look quite different to anything else on the market. It doesn’t feature the typical SLR shape with raised viewfinder triangle, instead the viewfinder is off-set giving the camera a flat(ish) top plate. The flash hot-shoe is in line with the lens mount. The on / off button is in a rather unusual position, and it can take a while to find it when you first pick up the camera, but once you’ve found it, it is easy to get used to this, and it feels solidly made. The camera has a metal body, that feels extremely well-built with rounded corners and edges, and the placement of the control wheels on top are very slightly moved away from the edges meaning you don’t accidentally catch them.
The sd Quattro weighs 625g without the battery or memory card. This is slightly lighter than the Sigma SD1 / Merrill, which weighs 700g, but more than the Sigma dp Quattro cameras weigh, at between 395-500g including the lens.
On top is the dioptre adjustment dial, control dial, lock switch, shutter release with another control dial, QS (Quick Set) button, flash hot-shoe, plus on / off switch next to the lens mount. The buttons and controls feel good, and the spacing between some of the smaller buttons makes it easy to change settings without accidentally pressing the wrong options. The QS (Quick Set) button makes it easy to change settings quickly on the rear screen, and you can customise what options are displayed so that you can access your favourite settings quickly.
There are 9 focus points, and you can also use the “Free move” focus option to move the focus point more precisely.
The menus are well laid out and clear thanks to the high resolution screen, and the different sections are colour coded. There is no built-in help, so it’s advisable to familiarise yourself with the manual. The back has buttons for the display, a switch for the viewfinder / auto / monitor, a playback button, S/C (single / continuous) auto focus, AF/AEL lock, sub monitor light on/off button, exposure compensation, ISO, metering, mode, 4-way controller with middle OK button, menu and focusing point button.
You can switch the rear screen off if you want, and just use the small sub-display, and you can also switch this off, so nothing is displayed on the rear of the camera. The screen, secondary display, and EVF can be set to automatically adjust the brightness depending on ambient lighting conditions, or you can set it manually. The colour reproduction on the screen and EVF match each other, but the resolution is quite blocky. Viewing angles of the screen are very good, and visibility is quite good even outdoors. The EVF is a high resolution 2.36 million dot unit, with an impressive magnification of 1.1x making the view appear large, however the refresh rate from the sensor isn’t very quick which makes the viewfinder appear jerky, and not very smooth, as well as being quite coarse.
The performance section is where we look at the image quality performance of the camera. Additional sample photos and product shots are available in the Equipment Database, where you can add your own review, photos and product ratings.
Speed – We took a number of shots to test the camera’s responsiveness, from switch on to first photo, shot to shot, focusing speed etc. We take a number of shots and then use the average to ensure accurate and consistent tests, making it easy to compare with other cameras.
|Wide – Focus / Shutter Response||1.2secs|
|Switch on Time to Taking a Photo||3.85secs*|
|Shot to Shot without Flash||1.0secs*|
|Continuous Shooting – JPEG
(shots before slow down)
|3.7fps (12 shots)|
|Continuous Shooting – RAW||3.7fps (12 shots) (1min)|
Shutter response is quick, however focus is quite slow, and it would be good if this could be improved with a future firmware update. We tested using the central focus point, and used the Sigma 30mm f/1.4 DC Art lens. *Switched to manual focus. 1 minute to write 12 raw files to the memory card after shooting.
Sample Photos – For best results, processing the raw file is recommended, particularly if you want to control how the image looks, however, the camera does a reasonable job with JPEG output. Raw files are between 47 and 58MB in file size, with JPEG images between 10 and 14MB. Exposure is reasonably reliable, however it was confused at times, and recovering the image from the raw file was straightforward.
There are options to adjust the colour, with specific control over contrast, sharpness and saturation. There are a number of presets as well.
Lens Performance – The main reason why processing the raw files is recommended is due to chromatic aberration which isn’t automatically corrected in camera. Centre sharpness is excellent from the Sigma 30mm f/1.4 DC Art lens, becoming software towards the corners of the frame. A large lens hood is provided which helps avoid flare.
Levels of detail captured is very good, with resolution and detail captured equalling cameras with much higher resolution sensors, such as the Nikon D810 (36mp), and coming close to cameras like the Sony A7R II with 42 megapixels. However, images also show quite a high level of noise in shadow areas, and further noise reduction is recommended in software.
The “Super Fine Detail” mode creates a 344MB X3I raw file, that can only be opened in Sigma Photo Pro. Processing these images is slow and time consuming. However, the image definitely shows much less noise than standard shots taken with the sd Quattro, a little more detail, and better dynamic range.
ISO test images
ISO Noise Performance – ISO shots taken at ISO100 and ISO200 show the lowest levels of noise, however when trying to recover shadow detail, noise is more visible, and we wouldn’t recommend using ISO400 or above, unless you plan on further processing of images. The higher ISO settings might be useful in a situation where you need to take the shot and don’t have any other option, and in these situations you would be best resizing and converting the images to black and white.
White-balance test images
WB Tungsten | 1/13 sec | f/5.0 | 30.0 mm | ISO 100
AWB Fluorescent | 0.3 sec | f/5.0 | 30.0 mm | ISO 100
AWB Lighting Priority Fluorescent | 0.3 sec | f/5.0 | 30.0 mm | ISO 100
WB Fluorescent | 0.3 sec | f/5.0 | 30.0 mm | ISO 100
White Balance Performance – Auto White Balance (AWB) gives a warm result under tungsten light. With the normal and AWB Lighting Source Priority option selected the result is warmer again. The Tungsten preset gives a more accurate result, but for the best results manual white balance or raw processing is recommended. The AWB performs well under fluorescent lights, with the AWB Lighting Source Priority option giving a warmer result, and the fluorescent preset giving a slight colour cast. Again, for best results manual white balance or raw processing is recommended. The camera can struggle to produce good auto white balance results, and therefore shooting in raw becomes important.
Digital Filters – There are a number of colour profiles available. You can develop raw files in camera, and this lets you adjust exposure compensation, white balance, image quality and size, aspect ratio, colour mode, colour space, and tone control. There is no video mode. There is no panoramic mode.
|Sensor Type||Foveon X3 CMOS|
|Sensor Size (width)||23.4mm|
|Sensor Size (height)||15.5mm|
|Shutter speeds shortest||1/4000sec|
|Shutter speeds longest||30sec|
|ISO sensitivity||100 – 6400|
|Viewfinder Resolution||2,360,000 dots|
|Video FPS||No Data|
|Optical Zoom with Video||No|
|Battery Type||Sigma BP-61 Lithium-Ion 7.2V 1860mAh 14Wh|
|CIPA Rating||No Data|
|Box Contents||Li-ion Battery Pack BP-61, Battery Charger BC-61, AC Cable of Battery Charger, USB Cable, Strap, Body Cap, Instruction Manual, Limited Warranty, Warranty Sticker|
Value For Money
The Sigma sd Quattro is available for £799/$1,198 body only, or £999/$1,498 with the Sigma 30mm f/1.4 Art lens, which is quite good value for money. Certainly much better value for money than the SD1 Merrill which was around £1,600/$2,400. Alternative, high resolution mirrorless cameras available, include the following cameras, with the Olympus OM-D E-M5 offering a 40mp mode, and the Olympus PEN-F offering a 50mp mode:
Sony Alpha A6300, 24mp, APS-C sensor
Sony Alpha 7R II
Olympus OM-D E-M5 Mark II
Have a look at more cameras in our Top 13 Best Premium CSC Cameras 2016, and Top 10 Best APS-C Digital SLRs 2016. You’ll also need to buy an SD memory card and a case or bag to keep your camera safe and protected – have a look at our complete guide to camera bags.
The Sigma sd Quattro is a unique camera, that lets you use the Foveon sensor with any Sigma lens, and does away with the optical viewfinder and traditional Digital SLR styling. Sigma has decided that rather than continue with Digital SLR development, they would rather release a mirrorless camera instead, along with Hasselblad, and Leica. In fact, with just Canon, Nikon, and Pentax left as being committed to Digital SLRs, it’s interesting to see that fewer and fewer companies are selling DSLR cameras. The Sigma sd Quattro is a mirrorless camera, whilst still being a similar size to a Digital SLR, and for anyone who likes the size and weight of a Digital SLR, then the sd Quattro is likely to be a reassuring size.
For those that want impressive levels of detail in every shot, then the Sigma sd Quattro (and dp Quattro) series is an interesting choice, thanks to the unique Foveon sensor. However, you’ll also need to be prepared to use Sigma’s Photo Pro software, which is noticeably slow when compared to every other photo editing package. This can seriously slow you down, depending on how many images you want to edit, particularly as you will most likely want to continue editing the image in another software package such as Adobe Photoshop. It’s therefore recommended that you invest in a fast computer.
Somewhat disappointingly, the camera is best at ISO100, and using any higher ISO setting results in visible noise. There is also noise visible in images taken at ISO100, for example if you need to recover any of the detail in the shadows, then this too will show signs of noise. Something you don’t expect to see when shooting at the lowest ISO setting available on a camera. Focus speeds can be slow, and it will be good to see this improved in future with firmware updates.
It would also have been nice if Sigma had adopted a new lens mount, with a much shorter flange distance (the distance between the sensor and the lens mount), as this would have allowed the use of third party lens on the camera (much like you can with other mirrorless cameras). Sigma could have bundled an adapter with the camera to support Sigma lenses. With the camera having the same flange distance as the Sigma DSLR, this means the camera is a similar size to a Digital SLR, and doesn’t really benefit from the size advantages possible with most mirrorless cameras. Although if this was Sigma’s original intention, then they have succeeded, and the introduction of the secondary display is a nice touch, along with the good controls and solid feel of the camera.
However, saying all of that, if you have the patience to give the Sigma sd Quattro the time required, then it can reward you with some extremely sharp images. Sigma has also been producing a number of high quality lenses, and with the right processing, the camera should give some extremely pleasing results.