Sigma SD1 Merill 46Mp DSLR
Cut-price, hi-res hot shot
Review The Sigma SD1 might not be a household name but some of you will certainly be familiar with it. Launched at Photokina in 2010, the SD1 was the first and only DSLR to show off a sensor based on an entirely new technology. Albeit akin to an APS-C format, the SD1’s Foveon sensor was capable of capturing three times as much colour information than its rivals and consequently clocked up a 46Mp count.
Sigma's SD1 Merrill kitted out with the PG-31 power grip battery pack
Despite the ‘wow’ factor the Sigma SD1 was a commercial flop, not least due to the staggering £6000 price tag it carried at launch. Since then, Sigma has made a few firmware tweaks and relaunched a new version of the SD1 called Merrill, after one of the creators of the Foveon sensor.
So what is different about this latest release? The answer is quite straightforward: nothing, apart from the addition of the Merrill logo and a critically important reduction in price. Today, at a retail price of £1840, the Merrill is a fraction of the cost of the original SD1. However, it retains the same weather-sealed magnesium alloy body and that stonking 46Mp sensor along with all the other specs, including 11 cross-type AF points, 5fps continuous shooting, a 3in 460K-dot LCD screen and a maximum shutter speed of 1/8000th second.
With a much more reasonable pricetag, it looks like the SD1 Merrill can now compete with established APS-C DSLR models such as the Nikon D300s, the Canon EOS 7D or the Sony Alpha A77. So, second time around, this innovative camera deserves a closer look too see if the Merrill merits its own place in the professional and enthusiast DSLR market.
The SD1 definitely looks the part. The alloy body gives the camera a solid, professional and expensive look while the weather-resistant seals will definitely appeal to pro users. The design is extremely ergonomic with a deeply recessed front grip cut in the middle by an unusual but very comfortable deep groove where to rest your middle finger. This adds to the already secure grip and makes the camera feel very light in your hand.
A professional approach to the top plate layout
The layout of the controls is what you would expect from a professional DSLR with most of the functions being accessed directly from a button or dial. The top plate houses on the right the mode dial, which includes the usual PASM plus three user defined modes, the classic twin dials for full manual control and a number of dedicated buttons such as Metering, Exposure compensation, ISO, AF and AEL.
The twin dials unfortunately cannot be customised, keeping to the same functions regardless of the mode, so in semi-automatic modes one of them is always functionless and basically wasted. On the left of the top plate there is the drive mode dial, which doubles as on/off switch and includes options such as UP (a mirror-up mode) and AB – a bracketing mode that lets you define the bracketing increments of the auto bracketing.
A non-articulating LCD and no Live View either
A few other functional buttons are well placed at the rear and the side of the camera to control access to menus, playback and provide pro-like functions such as depth-of-field preview and flash compensation. The camera operation is intuitive although not always the most efficient - with some settings needing button activation and dial rotation at the same time – but all in all the SD1 Merrill remains a pleasant and user-friendly camera to use.
In use, the menus are well organised and easy to access. The main menu is structured into three brief sections that are accessed and scrolled through the four-way pad controller but the camera also offers two quick menus covering almost every setting you are likely to change during shooting. One is brought on by the Function button and consists of an interactive screen menu showing most shooting parameters on the same display, that can then be navigated with the right/left arrow buttons of the controller.
An array of buttons plus a dedicated function key aid menu navigation
The second is a Quick Set menu made of two tabs, each tab giving access to four settings. Since each setting is directly accessed by the directional arrow corresponding to its position on the display the QS menu offers a fast and immediate way to change shooting parameters.
The SD1 has quite a large and bright viewfinder through which all framing and focusing takes places since the LCD screen sadly lacks Live View. While I personally prefer to shoot through the viewfinder, sharp focus can in certain situation be obtained much more easily through Live View. Considering that the camera is particularly suited to studio work, where accurate focus on fine details is a must, the lack of such a useful focusing aid might prove a deal-breaker for some photographers.
At the heart of the SD1 lies Sigma’s 23.5 x 15.7mm Foveon X3 CMOS sensor. The technology used in the Foveon is completely different from all other sensors, as it is not based on colour filters to process and reproduce colour images. Exploiting the inherent differences in characteristics of red, green and blue light, the Foveon uses a system that captures colour data at three different levels with respect to the actual colour.
The Foveon adopts a layered approach to image capture rather than using a mosaic typical on most sensors
Basically the Foveon sensor uses three layers of pixels – around 15Mp each – to capture each of the primary colours directly before the final RGB image is created by combining the output of each colour layer. Adding these three layers together gives the 46Mp figure. However, the maximum image size remains at a 4704 x 3136-pixel maximum (around 15Mp), it's just this image has not been sliced and diced for RGB as a mosaic sensor would do.
There are immediate advantages to using a direct image sensor like the Foveon. As there is no need to demosaic the final pixel output – a process necessary in conventional sensors that capture colour data onto one single mosaic-patterned layer. Futhermore, there’s no need for an anti-aliasing filter – normally used to lessen the moiré effect of demosaic process but that lowers effective resolution. The images captured by the Foveon are naturally moiré-free and resolve more data detail than any other equivalent size sensor.
Sigma's utilises its own SA bayonet lens mount type in the Merrill
The upshot of the Foveon approach are images that have an incredible level of detail that outshines any other camera in this class and many full-frame models – at least at low sensitivities. The RAW files, in particular, are in a class of their own with perfectly balanced, natural colours and amazing definition. The JPEGs are also very well resolved in terms of detail and colour but seem to suffer from a consistent and annoying overexposure problem.
The main issue and the real stigma of this camera is that at higher sensitivity, anything from ISO 400 onwards, image quality deteriorates dramatically with unacceptable levels of noise appearing and with pictures generally falling far short of the standard of most APS-C cameras. The technical reasons behind this are too complex to summarise here but they are inherent to the technology employed in the Foveon.
Alloy body and weather sealed too
The peculiarity of a camera that produces top class images at low ISO speed and really poor results at higher sensitivity greatly limits its use in the real world. The SD1 is a camera that will work magic in studio or landscape photography but will be unsuited to most other fields.
Add to the high ISO noise problem the sluggish general operation, the slow and at times erratic autofocus system and the narcoleptic file writing speed and it becomes clear that this camera is not everyone’s ideal imaging tool. The lack of any sort of creative filter, effect and video mode will also seriously reduce the SD1’s allure for anyone but professional and seriously enthusiastic photographers.
Dare to be different
That said, there is one feature that will surely meet the favour of most photographers: the SD1’s ability to produce infrared images straight out of the box. The SD1’s unique personality shows in the clever idea of placing the IR filter, which also doubles as dust filter, at the front of the lens mount in a position where it can easily be removed to produce infrared images, something no other mainstream camera I know of can do.
Just a few lenses...
The SD1 ships with its own supplied software – Sigma Photo Pro – to process its X3F RAW files, which is an integral and essential part of the imaging system of the camera. The software is not very user-friendly to start with or very fast either, but it complements the camera’s image output brilliantly and is capable of fixing some of the issues affecting native files.
For example, the raw processor is capable to recover almost all the highlight details lost in the above mentioned overexposure problem and to perfectly convert the infrared shots, taken with the filter removed, into quirky Black and White images.
A unique sensor with unique characteristics – ideal for photographers with unique talents
Sigma uses its own lens mount, which means that the SD1 is only compatible with Sigma lenses. These are plentiful though – over 40 to choose from – and usually of very good construction, so the brand-specific mount should not be too much of a problem. I tested the DS1 with the Sigma 17-50mm f/2.8 EX DC OS HSM lens  which is a very decent standard zoom. Enjoying a f/2.8 constant aperture and a smooth zooming operation it is a solid and useful optic.
Battery life is nothing to write home about and considering the lack of video mode or Live View it is far shorter than I expected with less than 200 hundred shots per charge.
So what’s the final word? Is the Sigma SD1 worth the premium price tag it carries and the attention of professional and enthusiast photographers? There is actually no definitive answer to these questions. For landscape and studio photographers the SD1 will be an outstanding, unique camera worth every single penny.
But for most other photographers the numerous limitations of this camera will outnumber the advantages of the Foveon sensor and the superior image quality it delivers at low ISO. At best the SD1 will be a sought-after niche product but for all its weakness I truly believe it could be a great investment for the right photographer and I commend Sigma for trying walking a different path. ®
Catherine Monfils  is a professional photographer specialising in portraiture, lifestyle and fashion.
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