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Sigma DP2 Merrill Review
by Jim Keenan -  1/31/2013

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That "Merrill" in the product designation is in reference to the late Dick Merrill, an engineer and photographer who was a principal in developing the technology found in the DP2's sensor. And since we've mentioned the "S" word, let's spend a minute or two on a basic dissertation about the sensor in the DP2, since that is arguably one of the strongest selling points of this camera. In a typical digital camera the sensor gathers light at its photo sites called pixels - some pixels capture red light, some blue and others green. The sensor in the DP2, in SIGMA's words "..captures all primary RGB colors at each pixel location with three layers, which results in incredibly detailed images with a three-dimensional feel."

The design of the SIGMA sensor also permits the camera to dispense with an anti-aliasing filter found on virtually every other digital camera. Without going into engineering detail, the absence of an anti-aliasing filter, in theory, would be expected to slightly improve sharpness and resolution over an identical sensor equipped with an anti-aliasing filter. Improved sharpness and resolution, even slight, are good things.

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The DP2 joins the burgeoning large sensor/compact digital camera ranks, mounting an APS - C size sensor with a 1.5x crop factor and 46 megapixel (mp) resolution. It's those three layer pixels that are responsible for the hefty resolution advertised for this compact digital. The 3 inch LCD color monitor is becoming the benchmark size in this class, but elsewhere the DP2 strays from the typical compact digital recipe by featuring a fixed 30 mm/f 2.8 lens - zoom lens aficionados need not apply here. Applying that 1.5x crop factor, we come up with a focal length of approximately a 45mm lens in 35mm film equivalents - a focal length that nudges right up to the 50mm length that in film days was typically known as a "normal" lens because it provided a field of view approximately the same as that of the naked eye. If the fixed lens alone isn't enough to differentiate the DP2 from most of the compact digital crowd, the absence of automatic and scene shooting modes certainly does. Your only shooting options are program auto, aperture priority, shutter priority or manual exposure. And video users take note: at a time when full HD video is proliferating in compact digital cameras, the DP2 offers a relatively pedestrian VGA (640 x 480) video capture option at 30 frames per second. Finally, the DP2 separates itself from the compact digital pack even further by eschewing stabilization that is found in virtually every new camera in the class these days.

The camera accepts SD/SDHC/SDXC and Multi Media Card memory media and SIGMA includes a lens cover, camera strap, hot shoe cover, two lithium-ion batteries and charger, USB and A/V cables, a printed instruction manual and CD-ROM software with each camera. The DP2 originally entered the market with a $1400 MSRP; the current MSRP is $999. If the idea of spending nearly $1000 for a compact digital with a fixed lens, basic video, DSLR-style shooting modes and no stabilization sounds like your cup of tea, read on.

BUILD AND DESIGN

Outwardly, the DP2 follows the generic compact digital camera template and features a rectangular body, gently curved edges and the lens barrel protruding from the front of the camera. But while many compacts are found with a camera body about the size of a pack of playing cards or cigarettes, the DP2 has stretched its dimensions well beyond those parameters. The body is almost 5 inches wide counting the attachment lug for the camera strap, 2.75 inches tall and almost 1.25 inches deep; the lens adds almost another 1.4 inches to that depth on the front left side of the body. Shooting weight (battery, memory card, camera strap) is about 14.3 ounces, so while the DP2 isn't a candidate for shirt pocket carrying it does fit quite nicely into a jacket pocket (and the weight is not so onerous that carrying around the neck becomes a burden). The camera body is metal, made in Japan, has a solid feel and appears well-constructed.

Ergonomics and Controls

The rectangular body of the DP2 is finished in matte black paint that is fairly smooth, with no overt design features to promote a firmer grip on the camera. There is a small pattern of raised dots on the camera back in the vicinity of the thumb rest that provides a little bit of resistance to slippage - another grouping of similar dots on the right front of the camera body are positioned in such a way that my fingers never contacted them during normal use. The first order of business for a new DP2 owner is probably to attach the camera strap and have it around your neck when you're shooting in case you lose your grip on the camera.

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Once past the paint, the DP2 fit nicely in my hand, with the tip of the shooting finger falling directly onto the shutter button and the thumb settling in on the thumb rest area with no conflicts to other controls on the camera back.

The control layout on the DP2 is simple and well thought out - the top of the camera body features the hot shoe, power and mode buttons and a shutter button surrounded by the command dial. The left side of the camera back is taken up by the 3 inch monitor; arrayed vertically adjacent to the monitor are auto exposure lock/delete, quick set, menu and view buttons. Just to the right of this vertical configuration of buttons is a four-way controller including "OK", focus point and focus mode buttons. A display button at the lower right rear of the camera body can display various data configurations on the monitor while shooting, including a histogram. The manual focus ring on the lens was smooth and consistent in its operation.

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Menus and Modes

I found menus in the DP2 to be quite intuitive and easy to navigate. There are three main menus: capture settings, playback menu and camera settings. Pressing the menu button on the camera back takes you to the first page of the capture menu (four pages total), whose contents include settings such as ISO sensitivity, drive mode, white balance, image quality and size, color mode and color space, among others. Selecting any of these settings then produces a submenu for further actions. The playback menu is two pages long and the camera settings menu runs four pages. Vertical scrolling is accomplished via the four-way controller; horizontal scrolling via the command dial or four-way controller. Here's a look at the first couple pages of the capture settings menu:

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In another departure from a widely accepted practice these days among compact digital cameras, the DP2 does not provide a retouch menu that permits you to apply effects or modifications to images in the camera - the playback menu offers some simple commands such as "rotate", but there is not a lot of post processing to be done inside the DP2.

Pressing the quick set menu button allows quick access to eight camera functions via two submenus: ISO, metering mode, flash mode and drive mode on QS1 and white balance, image size, color mode and image quality on QS2. Shooting out in the field I made good use of the quick set menu for speedy shifts in camera settings, so here's a look at both pages. If you don't have a flash mounted on the camera the quick set menu doesn't permit you to access that function.

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Shooting modes are basic - pushing the mode button on the top of the camera provides users with the ability to select from video, manual, shutter priority, aperture priority, program auto or three custom settings. The custom settings allow you to preset three combinations of shooting settings, including all items in the capture settings menu, the four still image exposure modes (P, A, S, M), the focus point within the frame and exposure compensation. Here's a bit more detailed rundown on the shooting modes:

Display/Viewfinder

The 3 inch LCD monitor on the DP2 has a 920,000 dot composition and is adjustable for seven ranges of brightness. Even so, the monitor was hard to use in some bright outdoor conditions for both image composition and review - in this regard it was probably typical of most compact digital cameras.

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SIGMA makes an optional optical viewfinder for the DP2 and provided one for this review. The viewfinder mounts on the camera's hot shoe and has no diopter adjustment for varying degrees of eyesight. When shooting close-ups with the viewfinder (say, 2 feet or so from the camera to the subject) there is a bit of parallax to deal with. Because the viewfinder is mounted above the lens, at close range what your eye sees is not exactly the same perspective as that afforded the lens and the subject will not appear centered on the final image even though it appears so in the viewfinder when you initiate the capture process. Here are a couple of examples - the first was made using the monitor for image composition at about 1.5 foot distance and the second with the viewfinder from the same spot.

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I found that at a distance of about 10 or more feet from camera to subject that parallax was minimal and the final image captured by the camera closely approximated what I saw through the viewfinder. Inside of 10 feet from the subject I'd be inclined use the monitor for all shots, but beyond the 10 foot range you can fire away with the viewfinder and be quite certain that with proper framing within the viewfinder what you capture will be very close to what you see. I personally am not a fan of monitors for image composition and capture and if I were to pick up a DP2 the first accessory I would add is the viewfinder, even with its $200 MSRP. As we will discuss further in the performance section of the review, the addition of the viewfinder to the DP2 has a couple of collateral benefits over and above making it easier to compose images in bright outdoor conditions.

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PERFORMANCE

With a price tag that would get you into any number of entry-level DSLRs with kit lenses, how does the rest of the DP2's performance match up with its DSLR-sized sensor?

Shooting Performance

The DP2 loses the startup time race to a DSLR handily, taking about two seconds to display a focus point on the monitor. I was able to power up and get off a first shot in about 3.5 seconds, in the ballpark for the compact digital class. Single shot-to-shot times ran about two seconds. I used a 32GB Lexar 600x speed SDHC memory card for this review, and write times for a single JPEG fine quality, high resolution image ran about 8 seconds. The same shot taken as a high-resolution RAW file took about 13 seconds to write. You don't have to wait until the preceding image is written to capture another photo as long as there's room in the camera buffer - the buffer capacity is 7 images in JPEG fine, RAW, or RAW/JPEG quality at the highest resolution. Buffer capacity jumps to 14 images if you downsize to medium resolution.

The DP2 offers 4 frame per second (fps) continuous shooting rates at high resolution, and 5 fps if you drop down to medium resolution, subject to the same 7 and 14 image capacity buffer restrictions. Write time to completely clear the buffer for a 7 burst of RAW files at high resolution took 45 seconds; 33 seconds for JPEG fine. Write times using a 16 GB 400x Lexar card were similar for both single and continuous shooting modes, so it appears you can save a little money by going with a slightly slower card without compromising the camera's writing performance.

Just as with single shot mode, the DP2 will allow you to continue shooting bursts as soon as there is room for two or more images in the buffer - you can also take a single image once the buffer has room. One drawback with the continuous shooting mode in the DP2 is that there is no continuous autofocus; the camera establishes focus with a first shot of a burst and maintains it for the rest of the burst. If your subject is moving but stays at approximately the same distance from the camera as the initial shot you should have no worries, but subjects moving towards or away from the camera may not stay in sharp focus for the entire sequence.

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Continuous shooting is where the first collateral benefit of mounting a viewfinder on your DP2 comes into play - when shooting in continuous mode the monitor goes blank as you capture the first image and stays that way for the balance of the burst. With the viewfinder attached you're able to track moving subjects as the monitor blackout does not carry over to the viewfinder.

Whether you're shooting single frames or continuously, the lack of stabilization in the DP2 takes you back to an age where camera shake was a major factor in images that came out less than tack sharp. Back then we had a rule of thumb for the minimum shutter speed you'd like to use with any particular lens focal length in order to minimize the effect of camera shake during hand-held shooting. The rule is simple and basically stated that you use at least the inverse of the lens focal length as the minimum shutter speed in seconds - for example, if you're shooting a 25mm lens you would like to have a minimum shutter speed of at least a 1/25 of a second. Shorter shutter speeds are always better where camera shake is in play, and in the case of a DP2 shooting at approximately 45mm in 35mm film equivalents, 1/50 a second would be the minimum you'd try to use. Not surprisingly, the DP2 displays a red camera shake warning on the monitor whenever shutter speeds fall below 1/50 of a second. Here's the other collateral advantage of having the viewfinder on your DP2 - you're holding the camera up to your face in order to look through the viewfinder and are able to brace your arms on your sides and also the camera on your forehead, promoting a more stable hold that may allow you to shoot a bit slower than the suggested shutter speed without impacting camera shake.

The DP2 has some other nice features for more advanced users, such as exposure compensation and a three shot auto bracketing capability.

Autofocus times with the DP2 were a mixed bag, generally being fairly quick in good lighting conditions, but even then sometimes hunting a bit if the focus point was centered on a subject that was dark-colored. In dimmer light the DP struggled, a not uncommon occurrence for compact digital cameras- when the camera did acquire focus in dimmer light it tended to be only after it seemingly ran the lens through a range of focus distance. There is no focus assist lamp on the camera. Manual focus is a bit tedious, requiring over a full turn of the focus ring to go from the close focus point to infinity - but the good side of this is it makes fine-tuning the focus easier once you get close to the optimal focus distance.

Shutter performance seemed to show just a tiny bit of lag, but my feeling on this may have been influenced by the timing of the shutter sound accompanying the full push of the shutter button. In any event the DP2 captures the picture fairly promptly when you tell it to.

SIGMA makes an optional flash for the DP2 but we did not have one available for this review. This flash has a maximum guide number of 14m (about 46 feet) at 100 ISO and can be used in Program Auto shooting mode only. In addition to its normal flash setting the flash provides redeye reduction, slow synchronization, and redeye reduction with slow synchronization settings. Flash exposure compensation is also available.

Back in the introduction I mentioned that Sigma provides two lithium-ion batteries with the DP2, but there's a good reason for this: battery life in the DP2 is short, to say the least. Sigma rates the DP2 as having a 97 image battery life, but in one stretch where I was doing some (but not a lot of) image review and a bit of menu surfing, the battery was exhausted after 72 images were captured. While shooting at Disneyland with minimal image review and shutting off the camera between shots I managed 72 still images and a couple of 15 second videos before my first battery completely drained. About a dozen of the 72 stills were five second exposures in a dim restaurant setting, but suffice it to say you probably cannot have too many batteries along on an all day shooting session with the DP2.

Lens Performance

The 30mm lens on the DP2 is fixed, but no matter - you wouldn't want to replace it if you could. I observed excellent optical performance from this lens, with good sharpness throughout the entire frame and possibly just the tiniest bit of softness in the corners. I took about a half-dozen captures subjecting the lens to scenes that would tend to promote chromatic aberration with no negative results to report. Distortions such as barrel or pincushion are not apparent in images with straight lines deliberately composed toward the edges of the frame. In a perfect world SIGMA might have made this lens a little faster than f/2.8 to help take up some slack for that lack of stabilization, but given its optical excellence f/2.8 is not too onerous a price to pay. SIGMA notes that the lens does its best work at f/5.6 and f/8. Here's a couple looks at images with texture throughout the frame that allow you to get an idea of the sharpness of this lens from edge to edge.

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I do have one gripe that is lens related, however, and it is that SIGMA has seen fit to make the lens hood an optional accessory rather than including it as standard equipment. Come on guys, you're getting $1000 for this camera, the least you could do is include a $40 lens hood.

Video Quality

Despite that excellent lens the DP2 video performance is nothing to write home about. With even entry-level compact digitals boasting 720 HD video these days, the DP2's 640 x 480 VGA resolution and mono sound are decidedly off the pace. Despite its unique pixel construction the sensor on the DP2 is still a CMOS, and as such may be susceptible to rolling shutter effect. Actually, there's no "maybe" about it - the DP2 generates a fair amount of rolling shutter in images that are panned at exaggeratedly fast paces. You wouldn't ordinarily pan at such high speeds, but if you're capturing a video of a fast-moving object don't be surprised if vertical subjects in the background appear skewed as the camera pans past them. Another knock on the DP2 video is that there is no continuous autofocus - focus is established with the initial pressing of the shutter button to focus and initiate capture, and remains at the same point for the balance of the clip. In fact, even if you're in manual focus whatever distance you chose as the initial focus point remains for the balance of the clip - you can't manually change focus to account for varying distances with your subject during video capture.

Image Quality

What the DP2 does well, really well, are still images. Default images out of the camera were very pleasing as to color rendition and sharpness, but there are myriad adjustments available if the default settings don't meet with your approval. This camera unquestionably produces the finest still images of any compact digital camera that I've reviewed. I'm not sure if I go so far as to agree with SIGMA's assessment that the unique sensor of the DP2 produces images with a near 3-D quality, but images out of this camera are just gorgeous, be they RAW or JPEG. Here's a look at two JPEGs; the first was a raw file converted to a TIFF file and later a JPEG - the second a JPEG fine straight out of the camera.

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While SIGMA advertises the resolution of the DP2 sensor as 46mp, they quietly acknowledge that this rating is a product of the unique three-dimensional RGB design of their pixels and that the calculation for resolution of their sensor, known as a Foveon, differs from the traditional CMOS sensor, known as a Bayer. Sigma evaluates the DP2 sensor as comparable with a Bayer sensor with a resolution of 26 to 30 megapixels. Whatever the actual resolution of the DP2 is, the still image quality speaks for itself.

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The DP2 offers a color palette including standard, vivid, neutral, portrait, landscape, B&W and sepia options - but B&W and sepia are not available when shooting RAW files. Here's a look at that palette:

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Standard                                                                           Vivid

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Neutral                                                                             Portrait

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Landscape                                                                         B&W

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Sepia

Auto white balance was used for virtually all the images captured for this review and worked well across a range of light with the exception of incandescent, which shot a bit warm. The DP2 also offers daylight, shade, overcast, incandescent, fluorescent and flash preset values along with a custom setting.

Evaluative metering is the default exposure calculating mode, and divides the screen into 256 segments to analyze for determining the correct exposure. The system did a pretty good job under most lighting conditions, although it did have a bit of a tendency to clip some highlights in high contrast scenes. This performance is not unusual for compact digital cameras and when I looked closely at histograms for some of the scenes it appears the DP2 strikes a fine balance between highlight and shadow, setting exposure so that there's just a little bit of highlight lost while at the same time minimizing the amount of shadow detail that is lost. The camera also offers center weighted and spot metering options.

High ISO noise performance with the DP2 was unimpressive.

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ISO 100                                                                             ISO200

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ISO 400                                                                             ISO 800

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ISO 1600                                                                           ISO 3200

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ISO 6400

100 and 200 ISO levels are virtually indistinguishable from one another, and 400 is quite close although with 100% enlargement pixel peeping you can see a tiny bit of grain starting to appear. 800 drops off a bit from 400 although it's still fairly good, but close scrutiny shows that noise is definitely beginning to appear - if you have the option to satisfactorily make the shot without resorting to 800 ISO, by all means do so as the 100 to 400 ISO range is clearly the strength of this sensor. That having been said, here are two versions of the same five second exposure of the International Space Station as it passed over California. The capture was taken at 800 ISO and the first version is the JPEG fine image as it came directly from the camera - the second has been post processed in Photoshop CS5 with a bit of noise reduction, added contrast, saturation and sharpening over and above the original capture.

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The DP2 sensor has clearly hit the wall at 1600 ISO - increased grain and colors are dramatically beginning to fade, and the 3200 and 6400 settings continue the dramatic downhill trend. Colors have faded so badly at 6400 that the image is almost a black and white. As mentioned earlier the DP2 does not have stabilization, so keeping shutter speeds up to help thwart camera shake can be helped by shooting the camera at 200 ISO whenever possible - this gives you quicker shutter speed than identical camera settings at 100 ISO with little, if any noise penalty.

It's interesting to note that if you have the DP2 set to Auto ISO the camera will select from 200, 400 or 800 ISO in calculating exposures. You cannot select Auto ISO in the manual (M) shooting mode - the camera selects 200 ISO if you switch into manual from any of the other auto modes with Auto ISO selected. SIGMA recognizes the DP2 just doesn't do very well with ISO settings above 800.

Additional Sample Images

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