The 14-megapixel SD14 is the third DSLR from Sigma to employ the unique triple-layered Foveon sensor. Has the company got it right this time?
However, while other manufacturers relied on familiar Bayer-pattern CCD designs, Sigma found its own way, with a little help from sensor manufacturer Foveon and this continues with its third SD model – the SD14. Rather than using a grid of red, green and blue filtered pixels the Foveon CMOS sensor uses silicon, which naturally absorbs the three different wavelengths of light to different depths. By placing pixel sensors at these three discrete depths the Foveon X3 sensor is unique in that it can capture full colour information at each and every photosite, where other sensors will only record a shade of red, green or blue.
This means images from Sigma’s cameras don’t need to go through complicated (and sometimes destructive) interpolation routines to generate a full colour image. As a result, Sigma claims its digital SLRs are capable of delivering better detail and fewer colour artefacts than its rivals, while the tri-layered construction of the sensor effectively triples the camera’s resolution. With the SD14 this means the 4.64 million ‘pixels’ on the sensor translate to a 14MP image… Or do they?
Out on a Limb
Like Sigma’s previous DSLR excursions the SD14 includes two technologies that are unique to the manufacturer – the first being the lens mount and the other the sensor. In terms of the lens mount it’s not that surprising that the Sigma SD14 uses Sigma’s own SA lens mount. This gives the photographer the pick of Sigma’s lens line-up, with a 1.7x focal length magnification resulting from the size of the SD14’s sensor.
In this instance the imaging chip in question is a Foveon X3 CMOS measuring 20.7×13.8mm. Due to the unique structure of the Foveon sensor, Raw files are output at a 2640×1760 pixel resolution (4.64MP total), although Sigma claims this is the equivalent of a 14MP image due to the triple-layer construction.
Unlike previous Sigma DSLRs there is now the option to record JPEG files, with four size options on offer. At the top end of the range is ‘super high’, which delivers a 4608×3072 pixel image (14.15MP), with a ‘high’ option below it delivering images matching the Raw 4.64MP file size noted above. It’s a shame Raw and JPEG files can’t be recorded simultaneously though. ‘Flat out’ the SD14 can shoot JPEG images at a rate of three frames per second, although this will only be maintained across six ‘high’ quality JPEGs. If you need a greater burst depth then reducing the image size to ‘medium’ (2.1MP) will deliver 12 consecutive frames, while 24 shots can be taken using the ‘low’ (1.03MP) JPEG setting.
Aside from the SD14’s new-found ability to record JPEG files a further evolutionary step comes with the inclusion of a 5-point AF system. This might not sound like much, but considering the SD9 and SD10 had only a single AF point it should certainly help with focusing on off-centre subjects.
Yet ultimately the SD14’s feature list is a rather spartan affair, with functionality rather than unnecessary gimmicks being the order of the day. The shooting modes encompass the Program, Aperture Priority, Shutter Priority and Manual quartet to provide as much control over your image making as you might require, while eight-segment evaluative, centreweighted average and centre metering (large spot) patterns cover the exposure-making decisions.
Sensitivity and White Balance
In order to ensure you can get a sensitivity to suit the lighting conditions the ISO runs from 100 to 1600 equivalents in full steps, and although there isn’t an ‘extended’ ISO 3200 setting the given range is all that most people will need. The white balance system is equally utilitarian compared to some cameras, with an automatic WB setting joined by six presets and a custom option that allows you to set your own neutral tone using a white or grey card. The appearance of your image can be further adjusted with changes to the saturation and contrast (±1 in 1/10 steps) and with the choice of AdobeRGB and sRGB colour spaces depending on whether you want to go straight to print or fine-tune the results first.
Other useful inclusions – especially for flash users – are a built-in flash with a guide number of 11 (GN11m@ISO100), a hotshoe that delivers TTL flash control over compatible (that is, Sigma) flash guns and a flash sync socket on the side if you want to use a manual flash unit or studio lighting.
Like the features housed within
it, the SD14’s appearance is purposeful rather than ‘pretty’ and like
Marmite you’ll either love it or hate it. In the WDC office opinion is
mixed. One colleague described it as looking ‘unfinished’, while
another described the multi-faceted, matt black shell as ‘brutal’. The design may appear to be a little industrial,
but it’s also incredibly ergonomic. The right hand grip is fine for
most hands, allowing your thumb to naturally curl round the back to
rest in the rubberised indent on the rear. Add a reassuring weight
(that isn’t overly heavy) and a great balance and in the hand this is
one of the finest feeling cameras we’ve come across in quite some
It’s not just the physical presence of the
SD14 that’s appealing though, as the control layout is equally well
thought out. On the top plate to the right is a chunky main mode dial,
with the shooting options clearly picked out in white, while to the
left of the pentaprism is a second dial that acts as both a power
switch and a means of setting single / continuous shooting, the
self-timer and exposure bracketing.
This‘ transparent’ design – whereby the camera appears to wear all its functions on the outside – extends to the rear of the body, with a
single button taking you straight to ISO, white balance, image quality
and image size. This is exactly the type of control that many like,
with most of the features within a button-push encouraging the
photographer to try new settings and experiment more.
Rounding off the design – and again going back to
the ‘industrial’ feel of the camera – we have Sigma’s answer to dust
prevention, which is a simple, yet effective measure. The company seems to have little time for fancy gadgetry and simply fits a filter in the lens mount. The idea is that any dust trying to get into the camera
will be stopped like a fly trying to get into your house through a
closed window. Once settled on the filter, the dust is far enough from
the sensor to be rendered out of focus until you give it a clean.
Unlike the previous models the dust protector is now removable, so
should you find anything gets onto your sensor (from inside the camera)
you can still get to the Foveon chip to clean it the ‘traditional’ way with a sensor wipe kit.
When it behaves itself, the AF system can lock on quite swiftly, but this isn’t guaranteed. All too often the SD14 moves the lens (as if focusing) then proudly illuminates an AF point in the viewfinder to indicate it has locked on when quite clearly it hasn’t. At other times it will make the lens twitch and spasm for a frustratingly long time as it tries to lock on its target (often unsuccessfully). On occasion it doesn’t even do that – you half-press the shutter release expectantly and… nothing. No lens movement, no AF confirmation, it just doesn’t bother. Setting a single AF point seems to rectify this to some extent, but even with one active AF point there are still ‘false’ focus confirmations and tedious hunting episodes.
Poor LCD Screen
When it comes to reviewing your images, after a second or so the first image pops up. Scrolling through your shots is a relatively brisk exercise, and we particularly like the dual ‘compact camera style’ zoom in / out buttons on the back. However, the whole experience is let down by the woeful rear LCD screen, and we have to question why Sigma thought to fit a ‘high end’ DSLR with such a poor screen. The 2.5in size is fine, but the LCD’s 150,000 pixel resolution isn’t, making images appear ‘grainy’ on playback and menu text decidedly jagged around the edges. There’s just no excuse for this – countless compact cameras contain 250,000 pixel 2.5in LCDs, as do most ‘entry level’ DSLRs. The SD14 should too.
Yet despite the failings of the LCD and the AF system there is a glimmer of light at the end of the matt black SD14 tunnel – the pentaprism viewfinder. Offering 98% coverage it shows you virtually everything that will appear in the final image and the view is bright. Not only that – it’s also easy to see the corners of the frame and the green LED viewfinder information at the same time, so you don’t have to move your eye around, which is again excellent. Ultimately though, this is only a small consolation for one of the weakest performances we’ve experienced for a while.
How Many Pixels?
When it comes to the SD14’s image quality we probably have to decide first of all exactly what type of images we’re looking at. In the past Sigma would describe its cameras in terms of the number of pixels on the sensor, so the SD10 was described as a 3.4MP camera, capable of delivering an image equivalent to 10MP thanks to its triple-layered Foveon sensor. With the SD14, Sigma has dropped any reference to the 4.64 million pixels on the 3-layer sensor and decided to simply describe it as a 14MP camera instead – perhaps to avoid confusion, or possibly to play the ‘numbers game’, where consumers think a higher resolution equals ‘better’ images.
Unfortunately, regardless of what Sigma chooses to say, Adobe Photoshop’s Camera Raw plug-in thinks differently and opening up a Raw file in Photoshop gives an image measuring 2640×1760 pixels – a total of 4.64 million pixels. The good news is that images are generally pleasing at this resolution, with crisp edges and good detail making it possible to enlarge shots recorded at low ISO settings to an A3 print size.
Poor JPEG Quality
The same cannot be said of 14MP JPEG files, which stretch Sigma’s resolution claims somewhat. The problem appears to be the interpolation required to generate this file size, which results in ‘jaggies’ appearing along the edge of curved image elements and an overall softness that obliterates fine detail. Contrasting with this it’s noticeable that well-defined, high-contrast edges receive a significant level of sharpening, producing hard outlines that make the edge appear as if it’s been cut out with a sharp scalpel. Hard edges and a lack of detail just isn’t a pleasant combination.
We have few complaints regarding noise at the lower ISO settings though, which is minimal up to ISO 400. However, at ISO 800 unusual purple and yellow ‘blotches’ start to creep into the image. This isn’t the granular noise we are used to seeing in other cameras, but distinct patches of false colour that begin to disrupt neutral tones in an A4 print. At ISO 1600 things are worse still, with many shots exhibiting distinctly blue shadow areas that are obvious even when viewed as thumbnail images.
This isn’t helped by an automatic white balance system that often can’t quite make up its mind what colour balance to set, with consecutive shots of the same scene commonly displaying two different colour biases. However, to end on a positive note the SD14’s metering system is a match for most subjects, so at least you can rest assured that your images will be correctly exposed. It’s just a shame about everything else…
We don’t mind that the SD14’s specification isn’t groundbreaking because what’s on offer is all you need to take a photograph. There aren’t the distractions of scene modes or features that you’ll never use or need, making this camera the closest thing to a ‘manual’ DSLR that we are likely to see and it makes a refreshing change.
Unfortunately, what features the SD14 has got just don’t seem to have gelled together this time round. While the metering system is sound, the automatic white balance is unpredictable, the AF is lacklustre and the overly soft images (especially 14MP JPEGs) make picture-taking less pleasurable than it should be.