Better known for its lenses than cameras, Sigma has been producing both compact cameras and DSLRs for decades.
The Sigma DP1 Merrill is the latest in a line of compact cameras, and, similar to the previous DP models, it’s not your average compact.
With a fixed 19mm lens (equivalent to 28mm), no built-in flash and only VGA quality video, it lacks many of the features you’d expect in a compact camera, especially one with a premium price-tag.
But it’s what lies inside the Sigma DP1 Merrill – priced at £799.99/AU$950/US$999 – that really makes it stand out from the crowd.
At the heart of the Sigma DP1 Merrill is the same APS-C sized Foveon X3 sensor as the Sigma SD1 Merrill DSLR, which is quite unlike the Bayer sensor design used by almost every other digital camera on the market.
Instead of separate pixels sensitive to red, green and blue colours, which are then processed by interpolation to make a full-colour image, the Foveon sensor is made up of three layers.
This means that each pixel is effectively capturing all three colours, so the image doesn’t have to undergo any interpolation to render a full-colour result.
This sensor also doesn’t require an anti-aliasing filter, which can reduce the amount of detail a normal Bayer sensor can resolve.
This Foveon X3 sensor design makes it difficult to compare the resolution to other cameras. You’ll see that the resolution is quoted as 46MP, but it’s not quite that simple, since when you open an image from the Sigma DP1 Merrill you’ll find that they are actually 4704 x 3136 pixels.
So, in traditional terms the images are 15MP, but because each pixel is made up of three layers, the effective pixel count can be considered as 46 million.
The 19mm lens offers a maximum aperture of f/2.8, which isn’t the widest maximum aperture available on a compact camera, but does offer a reasonable option for low-light shooting.
The lens also has a manual focus ring, with a distance scale displayed on the rear LCD screen, along with nine individually selectable focus points for the autofocus.
If you don’t need the wide-angle capability of the Sigma DP1, the Sigma DP2 Merrill offers the same facilities with a 30mm (equivalent to 45mm) f/2.8 lens.
As you’d expect of a camera at this price, you get a full range of exposure modes, including Fully Manual.
There are also three metering modes, with the option of Spot and Centre-Weighted, along with the default Evaluative mode.
The range of ISO settings available are 100 to 6400, and the 19mm lens offers an aperture range of f/2.8 to f/16.
There is the option of shooting raw, JPEG or both together, with seven colour modes including Vivid, Neutral, Portrait, Landscape, Black and white and Sepia available in JPEG images.
The raw files are Sigma’s own X3F format, which can only be opened using the supplied Photo Pro software, since even older versions aren’t fully supported by any other software.
Build quality and handling
It doesn’t have the retro, rangefinder style of cameras such as the Fuji X series, but the body of the Sigma DP1 Merrill is simple, plain and smooth, with only the large protruding lens breaking up the square, boxy design.
There are small textured areas on the front and rear of the camera. This does make the camera as compact as possible, but we’d rather sacrifice the small size for a more reassuring handling of a handgrip.
Otherwise the basic handling is good, with a simple button layout, and easy access to most of the useful settings through either direct buttons or the QS (Quick Set) button on the back of the camera. You can also customise the functions accessed through the QS button to suit your preferences.
Being able to access the most useful functions through this button is a great idea, since the menu system can be slow to use as you have to scroll through each menu screen in turn.
There are two main controls on the Sigma DP1 Merrill that you use in most shooting modes, a dial around the shutter release and the left/right buttons of the four-way buttons on the back of the camera.
Normally the dial is used to change the aperture or shutter speed in aperture-priority and shutter-priority modes respectively, and the buttons change the exposure compensation.
While in manual, the dial controls the shutter speed and the aperture is changed using the buttons. In all of these modes the function of the dial and buttons can be swapped over as well.
With no optical viewfinder as standard, although there is an accessory viewfinder that fits into the hot shoe, you have to rely on the 3-inch LCD screen to compose your images.
The screen itself is clear and pretty easy to use, even in bright conditions, but it’s a little disappointing that the optical viewfinder isn’t a standard feature.
Even though the basic layout and operation of the Sigma DP1 Merrill is simple and neat, there are a couple of issues that spoil the overall experience.
The first is the time it takes to write images to the memory card. Despite having dual TRUE II processors, the Sigma DP1 is frustratingly slow when writing images to the memory card. When shooting individual images you can’t change settings for a second or so after each shot, as the camera starts writing the image.
You can continue to take shots during this time, but after the initial preview has disappeared the review facility is locked until the camera has finished writing. This can be three or four seconds for each image, which seems like an age compared to most current cameras.
The other frustration is the battery life, which in normal use with some reviewing of images, we found would go flat after as few as 65 shots.
To help overcome this, the camera is supplied with two batteries, but even so it’s not a camera that you can take to locations where you don’t have access to recharging facilities at the end of each day.
Much like the overall design of the camera, the results from the Sigma DP1 Merrill are a mixture of the sublime to the frustrating.
Let’s start with the good news, which is that in the right light at ISO 100 and 200, the Sigma can produce amazing quality images. The combination of the Foveon X3 sensor and fixed focal length lens combine to produce sharp, colourful and detailed images.
It’s not quantifiable, but the images in these circumstances have an almost three-dimensional quality to them. The colour rendition is also more than a match for even the best digital SLRs on the market.
But start shooting outside of the Sigma DP1 Merrill’s comfort zone and the results are much less impressive. At ISO 400 the images are still good, but they can’t compare with the images from most other cameras at this ISO setting.
Go above ISO 400 and the noise, colour saturation and detail deteriorate very quickly. The results at ISO 1600 and above are very poor, with very low saturation, high levels of noise and quite noticeable colour banding.
The autofocus is also quick and accurate in most conditions, although it can hunt a little in low light and when faced with low-contrast subjects, while the manual focus is easy to use.
The 19mm lens on the Sigma DP1 Merrill produces impressive results. In the centre of the frame, images are sharp at every aperture.
As you’d expect, the edges at f/2.8 aren’t quite as sharp as the centre of the frame, but they are still very good. There’s also very little distortion, and flare is well controlled.
There is some chromatic aberration visible in raw images processed without the lens corrections applied, although they are virtually eliminated when shooting in JPEG mode or when the corrections are applied to raw conversions.
Converted raw files also reveal a little more detail and sharpness than in-camera JPEG images, although there is a slight increase in noise.
The automatic white balance is good in daylight, but it struggles a little to produce accurate colours in artificial light and mixed lighting.
Similarly, the evaluative metering is reliable in most conditions, and on the rare occasions that you need to override the exposure in high-contrast lighting, it’s extremely quick to use.
Although it’s not strictly a feature of the camera, shooting images in raw mode means that you’ll have to use the Sigma Photo Professional software to process your images.
The basic layout and features are fine, but it’s not as user-friendly as other raw processing software.
While this is an improvement over the software supplied with previous Sigma cameras, it’s still slow to use and processing multiple images is a time-consuming and laborious task.
Image quality and resolution
As part of our image quality testing for the Sigma DP1 Merrill, we’ve shot our resolution chart.
If you view our crops of the resolution chart’s central section at 100% (or Actual Pixels) you will see that, for example, at ISO 100 the Sigma DP1 Merrill is capable of resolving up to around 24 (line widths per picture height x100) in its highest quality JPEG files.
For a full explanation of what our resolution charts mean, and how to read them, check out our full explanation of our camera testing resolution charts.
Examining images of the chart taken at each sensitivity setting reveals the following resolution scores in line widths per picture height x100:
ISO 100, score: 24 (Click here to see the full resolution image)
ISO 200, score: 24 (Click here to see the full resolution image)
ISO 400, score: 22 (Click here to see the full resolution image)
ISO 800, score: 22 (Click here to see the full resolution image)
ISO 1600, score: 20 (Click here to see the full resolution image)
ISO 3200, score: 18 (Click here to see the full resolution image)
ISO 6400, score: 18 (Click here to see the full resolution image)
Noise and dynamic range
We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using DXO Analyzer software to generate the data to produce the graphs below.
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
For more more details on how to interpret our test data, check out our full explanation of our noise and dynamic range tests.
JPEG signal to noise ratio
These results show that the Sigma DP1 Merrill’s JPEG files have a low signal to noise ratio when compared to those from the with the Panasonic LX7, Fuji X100 and Olympus XZ-2, coming in just above the Olympus at ISO 100-200, and bottom of the pile at the higher sensitivities that it was able to reach.
Raw signal to noise ratio
The signal to noise ratios of the TIFF images (after conversion from raw) from the Sigma DP1 Merrill are slightly stronger, beating the Panasonic LX7 throughout its whole sensitivity range, and the Olympus XZ-2 at ISO 100-200. It produced weaker results than the Fuji X100 at every ISO setting, however.
JPEG dynamic range
Raw dynamic range
This chart indicates that TIFF images (after conversion from raw) from the Sigma DP1 Merrill are second-strongest at ISO 100-400, sitting just below the Olympus XZ-2 and above the Panasonic LX7 and Fuji X100. It comes out top at ISO 800, the top of its measurable range.
Even shooting into the sun the metering gives good results, and the lens resists flare well.
Although the Sigma DP1 Merrill’s fixed focal length lens isn’t ideal for close-ups, the 20cm close focus is good enough to produce basic close-ups.
In good lighting, the Sigma SD1 Merrill produces bright, punchy colours such as the reds and greens in this shot.
The evaluative metering generally does a good job when faced with high contrast subjects, maintaining a good balance of highlight and shadow detail.
The Foveon sensor is capable of recording loads of fine detail, such as the veins of these autumn leaves.
This raw image shot at f/11 (processed using Sigma Photo Pro) shows that the 19mm lens has good edge to edge sharpness.
Landscape picture mode
The landscape picture mode boosts the colours, although there is a little more noise in the blue sky compared to the standard picture mode.
Sensitivity and noise
Full ISO 100 image, see the cropped (100%) versions below.
The Sigma DP1 Merrill is both brilliant and frustrating, depending on the shooting conditions and also your expectations.
The images in good light, at ISO 100 or 200, and especially shot in raw, are nothing short of superb, as the Foveon X3 sensor can reproduce detail and colours that even the best digital SLRs can struggle to match.
But that’s only half of the story, as there’s more to a camera than simply producing stunning results at low ISOs.
The results at ISO 800 and above are disappointing, and it doesn’t offer many of the features or performance you’d expect of a compact camera.
The slow write times and short battery life can spoil the picture-taking experience, and the reliance on Sigma’s own software for processing raw images can also be a time-consuming and less-than-ideal solution if you’ve got a lot of shots to go through.
The image quality at low ISO settings, particularly from raw files, is as good as many more expensive cameras, while the compact size, simple design and basic control layout are all impressive.
Above ISO 400 the image quality is disappointing, and the slow write times, battery life and reliance on Sigma’s Photo Pro software for raw processing can be frustrating.
Despite the simple, compact appearance, the Sigma DP1 Merrill isn’t really a point-and-shoot camera. It’s much better suited to a more considered approach to picture taking, and if that suits your needs you’ll struggle to find a camera that will produce better images, even if you spend much more cash.
If you can put up with the fixed focal length lens and slow write times, and want a compact camera that will produce amazing quality images at low ISO settings – especially from raw files – then the Sigma DP1 Merrill is a great choice.
By Chris Rutter, TechRadar