4:25 pm | September 25, 2012

Author: admin | Category: Cameras | Tags: AF, ISO, JPEG, LCD | Comments: None

Introduction

Would you pay £6,200 in the UK, or $9,700 in the US, for an APS-C DSLR that didn’t offer live view or video shooting, wasn’t compatible with third-party lenses and captured raw files that weren’t widely supported? That was the question posed by the 46 megapixel Sigma SD1 in June 2011.

We’re guessing that the positive answers didn’t exactly flood in, because 12 months later Sigma released a rebranded version: the SD1 Merrill. It’s a rebadged version of the same camera, offering identical performance but at a new, more sensible price. Cheaper manufacturing bills mean Sigma can offer the SD1 Merrill at the much sweeter cost of £1,840/$1,900.

Fortunately, Sigma is also offering a points reward system to photographers who forked out the price of a small car for the old model.

The Sigma SD1 Merrill is named in honour of the late Richard ‘Dick’ Merrill (1949-2008), the engineer who developed the Foveon X3 image sensor that’s at the heart of Sigma cameras.

Rather than being a ‘true’ 46MP sensor, it’s made up of three layers that each contain around 15.4 million pixels that are embedded in silicon. This design takes advantage of the fact that red, green, and blue light penetrates silicon to different depths.

This means that the SD1’s sensor captures full colour at every point in the image, rather than just red green or blue as with a standard Bayer pattern sensor. It’s this sensor, and its implications for picture quality, that’s the big draw of the Sigma SD1.

It needs to be, because otherwise the feature set is a little on the light side. There are no intelligent auto or scene mode frills here – it’s Program, Aperture Priority, Shutter Priority and Manual mode all the way.

Four options are provided for metering: Evaluative, Centre-Weighted, Centre Area (which only takes the region covered by the nine central AF points into account) and Spot.

The Sigma SD1 Merrill features an 11-point AF system. Each of these AF points can be selected manually using one of the control dials while looking through the viewfinder, or by using the four-way controller when viewing the AF point display on the rear LCD.

Focusing can be set to Single AF, Continuous AF (incorporating Predicative AF) and Manual. So far, so familiar.

Drive mode features a typical array of settings, too. Continuous Shooting mode is disappointing, rated at just five frames per second for a maximum of seven frames. This figure applies across the board for high resolution files, whether you’re shooting JPEG, raw or raw+JPEG files.

In addition to single-frame and continuous drive settings, two self-timer options and Auto Bracketing, the Sigma SD1 Merrill’s dedicated mirror lock-up function is worth noting. Select this and the camera flips the mirror out of the way when the shutter release button is fully depressed.

A picture can then be taken by simply half-pressing the shutter release again, meaning you’re less likely to jerk the camera and screw up the sharpness you’re trying to preserve with mirror lock-up in the first place – a nice touch.

Alternatively, the camera can automatically take a picture either two or 10 seconds after the mirror’s been moved.

Build quality and handling

The Sigma SD1 Merrill camera body itself is robust, and tips the scales at a not-too-heavy 700g. There’s little in the way of indulgent flourishes; more function over form, the Sigma SD1 Merrill’s utilitarian design does, however, feature some notable points of difference.

Take the grip, for instance, which includes a notch where a finger naturally comes to rest below the shutter button. Holding the Sigma SD1 for long periods is therefore a comfortable experience, despite the boxy feel.

The Exposure Compensation button is placed next to the shutter release button on the top lip of the grip, so this can be activated without taking your eye away from the viewfinder. In theory it’s a simple case of rolling your index finger from one to the other, but because the Exposure Compensation button is inset to prevent accidental operation, it can be slightly fiddly to operate.

Two chunky dials either side of the Sigma SD1 Merrill’s pentaprism control the key camera settings. The ‘D-dial’ on the left houses the drive mode options, one of which must be selected in order to switch the camera on.

The main Mode Dial, on the right of the pentaprism as you hold the camera, serves up the slimline selection of P, A, S and M modes and three Custom modes. The Custom modes enable you to tailor the Sigma SD1 Merrill to different situations by recording specific set-ups for Exposure Mode, AF Drive, White Balance Flash Sync and other parameters.

Elsewhere, a generous range of buttons and dials pepper the Sigma SD1’s body, providing quick access to the key controls. There’s not much in the way of doubling up of button functions, either. So metering mode, ISO, Autofocus, AE Lock and AF point selection get their own standalone controls.

Two control dials are used in conjunction with the buttons. The ‘A-dial’ is seated vertically behind the shutter release, while the ‘S-dial’ is a horizontal wheel on the rear of the thumb grip. The letter prefix gives a clue to each dial’s function in Manual mode, although their control over aperture and shutter speed can be swapped.

In the majority of other modes, they double up with the same function. This seems a wasted opportunity. Instead of both dials changing aperture in Aperture Priority mode, for example, why couldn’t one of them be configured to provide direct control over exposure compensation?

In addition to the dedicated control buttons, the Sigma SD1 Merrill offers two menu-driven control interfaces. Press the FUNC button, and the Function menu overview is displayed on the rear screen. Similar to Canon’s Quick Control Screen, this enables you to select a shooting parameter and change its current setting with the four-way control pad.

Too slow for you? Then try the Sigma SD1’s Quick Set Menu. Pressing the QS button to the right of the rear panel activates the first menu, where you can adjust ISO, metering mode, AF mode and flash settings. These are replaced by White Balance, Image Size, Colour Mode and Image Quality with another tap of the QS button.

Each of these functions corresponds with an arrow on the four-way controller on the back of the camera, and this is used to change the parameters directly. For instance, ISO is at the top of the first Quick Set screen, and pressing the up arrow begins cycling through the ISO sensitivities.

It can provide a very speedy way to react to a shooting opportunity, although having to repeatedly press an arrow key to cycle through options may come to irritate over time.

By far the biggest irritation, though, is the Sigma SD1 Merrill’s write times. During our tests it took an average of 16-17 seconds to process and write a file to memory card. Fill the camera’s buffer with its maximum seven full-res frames during Continuous Shooting mode and it takes around one minute 30 seconds to write the images to the card.

Compounding the frustration is the fact that some of the Sigma SD1 Merrill’s controls are unresponsive while the camera is clearing its buffer. Key shooting parameters such as aperture and shutter speed and exposure compensation are unaffected. But if you want to review the image or access the Function menu, you’re out of luck. Chances are, you’ll grow to hate the flickering red Busy lamp on the back of the camera.

Performance

So does the Sigma SD1 Merrill’s fabled Foveon X3 sensor make a difference? At low ISO sensitivities, absolutely. With careful raw processing there’s lots of fine detail to bring out, colours are rich and images have an overall smooth and silky, film-like quality that’s impressive.

However, edge towards ISO 1600 – a mid-range setting in the post-Nikon D3 world – and the Sigma SD1 Merrill’s firm grip on image quality loosens. Noise is a significant problem, creeping in at even lower sensitivities with JPEGs.

The Sigma SD1 Merrill’s .X3F raw files do fare a little better, but currently you can’t process these in mainstream software such as Adobe Camera Raw. Instead, they need to be converted in Sigma Photo Pro – a painfully underpowered and slow-performing slab of software.

This is a shame, because to get the best from the Sigma SD1 Merrill, raw files are in order. JPEGs straight out of the camera just look flat and unremarkable.

Carefully processed raw files do have the potential to look excellent, though. The 23.5 x 15.7mm 46MP (or rather, 15.4MP x3) sensor is no match for the larger 44mm x 33mm 40MP sensor in the Pentax 645D but, thankfully, the much cheaper price reflects this.

The Sigma SD1 Merrill can certainly deliver pictures with excellent dynamic range that give more expensive full-frame cameras a run for their money, at lower sensitivities at least.

Other areas of performance are a mixed bag. Auto White Balance errs towards the cool side, but focusing is quick and (most of the time) accurate. Exposure is also an area that requires regular manual intervention.

Like Canon’s iFCL metering system, the Sigma SD1 Merrill’s evaluative metering pattern seems to weight the exposure reading to the active focus point. This can lead to exposures that are too dark or too light, depending on which AF point is highlighted. Admittedly, if you use the camera for significant periods you grow accustomed to the metering system’s nuances, and can compensate as a result.

Image quality and resolution

As part of our image quality testing for the Sigma SD1 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 SD1 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:

JPEGs

ISO 100, score: 24 (Click here to see full resolution image)

ISO 200, score: 24 (Click here to see full resolution image)

ISO 400, score: 22 (Click here to see full resolution image)

ISO 800, score: 22 (Click here to see full resolution image)

ISO 1600, score: 20 (Click here to see full resolution image)

ISO 3200, score: 18 (Click here to see full resolution image)

ISO 6400, score: 18 (Click here to see full resolution image)

Raw

ISO 100, score: 24 (Click here to see full resolution image)

ISO 200, score: 24 (Click here to see full resolution image)

ISO 400, score: 22 (Click here to see full resolution image)

ISO 800, score: 22 (Click here to see full resolution image)

ISO 1600, score: 20 (Click here to see full resolution image)

ISO 3200, score: 18 (Click here to see full resolution image)

ISO 6400, score: 16 (Click here to see full resolution image)

Noise and dynamic range

We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using the DXO Analyzer software to give noise and dynamic range measurements at every sensitivity (ISO) setting.

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

A high signal to noise ratio (SNR) generally indicates a cleaner and better quality image.

Our lab tests indicate that the Sigma SD1 Merrill produces JPEG images that have a similar signal to noise ratio to those from the Canon EOS 5D Mk III, Nikon D800, Canon EOS 60D and Nikon D7000, at lower ISOs, but it drops off from about ISO 800 and above.

Raw signal to noise ratio

The Sigma SD1 Merrill’s raw files (after conversion to TIFF) start off with some of the highest signal to noise ratio values, matching the Canon EOS 5D Mk III up until the mid-range sensitivities, when it dips to scores closer to the Nikon D800, Canon EOS 60D and Nikon D7000. However, its performance is much lower than the other cameras at higher sensitivities (ISOs).

JPEG dynamic range

This chart indicates that the dynamic range of the Sigma SD1 Merrill’s JPEGs compares poorly with that of the Canon EOS 5D Mk III, Nikon D800, Canon EOS 60D and Nikon D7000 images. Though it starts off at the same point as the Canon 5D Mk III at ISO 100, it falls slightly below the Canon 60D until about ISO 400, when its dynamic range tails off sharply.

Raw dynamic range

This chart indicates that the Sigma SD1 Merrill’s raw files fare better than the JPEGs for dynamic range at low ISOs. It shows a greater range than the Canon EOS 5D Mk III, Canon EOS 60D and Nikon D7000 at low sensitivities, but begins a sharp fall after ISO 800. The Nikon D800 boasts better dynamic range than the Sigma SD1 Merrill throughout the whole range.

Sample images

Click here to see the full resolution image

Click here to see the full resolution image

Click here to see the full resolution image

The Sigma SD1 Merrill features seven colour modes – we used the Landscape setting in the shots above to accentuate the blues and greens.

Click here to see the full resolution image

Processing Sigma Merrill SD1 raw files in Sigma Photo Pro 5.2 is a slow experience, and the controls on offer are a little limited. It’s worth persevering, though, because the results have the potential to be much richer and more dynamic than JPEGs produced in the camera. Here, we added a touch of X3 Fill Light – it’s best to use this subtly, since otherwise it produces an effect close to overcooked HDR.

Click here to see the full resolution image

As with other Sigma DSLRs, the SD1 Merrill features a removable dust protector that sits just behind the lens mount. It’s generally an effective ‘first defense’ against sensor dust, although we noticed the blob you see here too late for our first batch of test shots…

Click here to see the full resolution image

Using the Auto White Balance resulted in an image that was initially much too cool, but switching to the Daylight preset yielded a colour balance that reflected the scene much more accurately.

Click here to see the full resolution image

We selected the Landscape Colour Mode in Sigma Photo Pro software to boost the blues and greens here. The Sigma SD1 Merrill comes with seven preset Colour Modes, including Standard, Neutral, Vivid and Black and White.

Oddly, you can’t select the Black and White option (or the Sepia one) when you’re shooting raw files or raw+JPEG. This means you won’t get a monochrome preview on the rear screen. Even more oddly, Black and White is listed under the White Balance options in Sigma Photo Pro.

Click here to see the full resolution image

Due to the darker conditions here, we had to shoot with a wide aperture at ISO 800. ISO 400 is about the limit for clean files out of the Sigma SD1 Merrill. This isn’t a camera for handheld shooting in low light, but keep to the ‘sensible’ end of the sensitivity range and it’s hard to be disappointed.

Click here to see the full resolution image

We found that the battery life indicator on the Sigma SD1 Merrill wasn’t entirely reliable – something to be wary of when shooting longer exposures. We managed to get around a day’s worth of shooting from a single charge (disappointing, but workable with a spare).

Click here to see the full resolution image

Exposure compensation can be applied in 1/3 steps from -3 to +3 EV on the Sigma SD1 Merrill. We needed to open up 2/3 of a stop to bring back the brightness to this overcast scene.

Click here to see the full resolution image

The Sigma SD1 Merrill’s 3-inch TFT LCD screen offers a 460,000-dot resolution for reviewing shots. This would have been considered very good a few years ago, but cameras such as the Canon EOS 7D are pushing over 921,000 dots these days. The playback information screen is a bit cramped too, particularly the RGB histogram, which can be difficult to judge accurately.

Sensitivity and noise

Full ISO 100 image, see the cropped (100%) versions below.

Click here to see the full resolution image

ISO 100

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ISO 200

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ISO 400

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ISO 800

Click here to see the full resolution image

ISO 1600

Click here to see the full resolution image

ISO 3200

Click here to see the full resolution image

ISO 6400

Verdict

According to Sigma, the Sigma SD1 Merrill is ‘for photographers who refuse to compromise’. We’d call that poetic license. You compromise on live view and video – standard features on the majority of DSLRs. You have to make allowances when it comes to shooting action, thanks to the achingly slow write times for the best quality files. You need to think twice before stretching the camera to ISO 1600 or above.

However, if you’re planning on doing lots of slow-paced, methodical photography in good light, where frame rates and high ISO performance don’t matter, then the Sigma SD1 Merrill represents a very fine offering indeed. It comes with a very capable sensor that produces some fantastic images.

We liked

The camera delivers on its picture quality promise at low ISO settings and, despite its lower ‘true’ resolution, it has the potential to outshine cameras with bigger sensors.

We disliked

Images may be sharp, but the performance in other areas isn’t. Picture noise debuts at lower ISO settings than we’d like, and the slow processing/write times can be crippling. There’s no live view either, so if you’re the kind of photographer who relies on this function for magnified manual focus, then you’re going to have to look elsewhere.

Final verdict

In terms of specification, the Sigma SD1 Merrill might lack the finery of other cameras at this price point, but its stripped back set of controls is refreshing.

Its limitations do mean that this isn’t a camera we can recommend as an all-rounder, though. If you’re after a DSLR that offers high resolution, high speed and high-spec features, look at the Canon 5D Mark III or Sony Alpha A77 instead. This way, you’ll also be able to use Sigma lenses without being restricted to a camera that just has a Sigma mount.

Both delightfully simple and deeply frustrating, the Sigma SD1 Merrill is the Jeckyll and Hyde of DSLRs. For photography in good light at low ISOs it’s absolutely terrific. For everything else, it’s just OK.