Sigma DP2 Merrill Camera

Why is it, I wonder, that I am drawn to offbeat cameras? Probably for the same reason I’m drawn to offbeat hi-fi gear. Oh, I’ve owned my share of stand-bys—Nikons of every variety, ‘Blads, Mamiyas, Sinars, Toyoviews, Deardorfs—but I’ve also taken the plunge on a number of oddballs, perhaps the foremost example being the very camera I’m about to talk about.

The Japanese Sigma Corporation is chiefly known for its Sigma-branded lenses, which at one time were considered the poor man’s substitute for the zooms and primes marketed by majors like Nikon and Canon. Nowadays, many of Sigma’s best lenses compete toe-to-toe with those majors. (And, for all I know, in addition to its own offerings Sigma may actually make some lenses for the majors—just as Voightländer and most Zeiss-branded lenses are made by the Japanese company Cosina.)

Up until about ten years ago, what Sigma has not been known for is making cameras. This began to change in 2002 when Sigma began to incorporate Foveon sensors, invented by Dick Merrill (thus the name), in its digital cameras. (Sigma acquired Foveon in 2008.)  

What is a Foveon sensor? Well, some of you may already know the answer to this, but for those of you who don’t perhaps the best way to explain it is to say that it is rather like the digital equivalent of color-slide film. Like slide film, which uses layers of photo-sensitive emulsions, each layer sensitive to different wavelengths of light, a Foveon sensor uses three stacked layers of silicon photodiodes (pixels), each with a different spectral sensitivity. Because different wavelengths of light penetrate silicon to different depths, each layer of photo-diodes records different colors—the topmost blues, the middle level greens, and the bottommost reds. The data accumulated by these three layers of photodiodes are then combined via image-processing algorithms to form a single RGB image. (Note that, like slide film, a Foveon sensor records RGB data for each pixel point.)

This is very different from the way that typical digital sensors (called Bayer sensors, after their inventor Bryce E. Bayer of the late, great Eastman Kodak Company) work. Bayer sensors are actually a mosaic of photo-diodes arrayed on a single, square, flat grid. Each photo-diode (pixel) is filtered to record only one of three colors—red, blue, or green. (For various reasons there are twice as many green-light-sensitive sensors as red or blue.) In order to create a full-color image from this mosaic of filtered sensors, the Bayer pattern must be literally de-mosaicized via algorithms that interpolate a complete red, green, and blue value for each pixel point. (Note that, unlike the Foveon, a Bayer sensor does not record complete RGB data for each pixel point; its RGB value is based on the level of red, green, or blue reported by those photosites adjacent to it.)

Because de-mosaicizing is not required in a Foveon sensor, the DP2M does not require an anti-aliasing filter (a thin piece of birefringent material placed atop the sensor to blur the moiré artifacts that the mosaic pattern of a Bayer filter would otherwise produce). Once you eliminate the anti-aliasing filter, which quite literally blurs the image, ipso facto you get a sharper, higher-resolution picture.

However, while a Foveon sensor has the potential advantages of truer resolution of colors and finer resolution of micro-detail, it also has a downside. The individual color-sensitive layers of the Foveon sensor do not filter colors as sharply as the filters on a Bayer sensor (which pass only one color and completely absorb the other two) do. This means that the data of the Foveon sensor must be further processed to eliminate common-mode signals, and such additional processing increases noise in low-light situations. To put this plainly, Foveon sensors function best in bright light (i.e., at low ISOs); they are not (and, as far as I can tell, by their very nature may never be) as good as Bayer sensors can be in low light.

A Foveon sensor (or, at least, today’s Foveon sensors) will not “see in the dark” the way the Bayer sensors in a Nikon D800E (or even a lowly Sony 5N) will. In fact, it won’t see “in the twilight.” Color fidelity and resolution go way down, and noise goes way up with decreasing illumination and increasing ISO. To take a night shot with the Sigma DP2 Merrill, you’re either going to need a flash or a tripod (and if you use a tripod you’re going to have to trigger the camera via its self-timer, as it has no cable or remote release).

While it isn’t fair to blame Sigma for the Foveon sensor’s inherent low-light limitations, there are other areas of the DP2M in which Sigma clearly lags behind the times and the competition. But before I come to those, let me describe what the DP2 Merrill is.

Basically, the DP2M is a $999 point-and-shoot camera—rectangular in shape with a very solid (though not weather-sealed) body made of aerospace aluminum. The DP2M comes equipped with a non-interchangeable 30mm f2.8 Sigma auto-focus (although there are also useful provisions for manual focus) lens. Unlike most p&s’s, the DP2M has an APS-C-sized (23.5 x 15.7mm), 46mp Foveon sensor.

Sigma, in its own version of the numbers game, likes to brag about the total number of pixels in its sensor, which is indeed 46mp. However, because, as I’ve noted, the Foveon actually comprises three layers of photodiodes stacked atop one another, each layer sensitive to a different color, one could argue with equal cogency that the DP2M is really a 15.3mp camera (i.e., 15.3mp/layer x 3 layers = 46mp total). One could argue this, I say, until one saw the images this camera is capable of producing. But we’ll come to that in due course.

To be fair, Sigma now claims in its advertising that, in comparative resolution tests, the DP2M is equivalent to a 30mp Bayer-sensor camera. (Confirmation of this can be found in Michael Reichmann’s DP2M review on Luminous Landscape—the best photography site on the Web. He thinks the DP2M is equivalent in resolution to the vaunted 36mp Nikon D800E or a 40-50mp medium-format camera in prints up to 20×24”. In any event, you must read his review of the Sigma DP2M at http://www.luminous-landscape.com/reviews/cameras/sigma_dp2m_review.shtml, which has single-handedly turned the DP2 Merrill into a back-ordered best-seller.)

As noted, the Sigma DP2M is equipped with a non-interchangeable (dedicated) 30mm f2.8 lens, which, with an APS-C-sized sensor, is roughly equivalent to a 45mm lens on a full-frame 35mm camera. While there are some obvious minuses to using a single fixed-focus lens, there are also some very significant plusses. A lens that has been expressly designed to take fullest advantage of a given sensor—and the DP2M’s lens has been—can maximize acutance, low distortion, and color fidelity, and this Sigma 30mm is a very very high-quality optic designed to wring every bit of resolution from the Foveon sensor. Using one aspherical and three high-refraction (what Nikon would call “ED”) elements, this eight-element, nine-bladed masterpiece produces an MTF curve that is very close to perfection. In optical quality, Reichmann claims it plays second fiddle to no other ”standard” lens from any other manufacturer including Leitz and Zeiss. Speaking for myself, the only other lenses I’ve had experience with that rival this one’s freedom from distortion and its extraordinary resolution of color and detail are large-format lenses from the likes of Schneider, Rodenstock, and Fujifilm.

While the DP2 Merrill has a unique and extraordinary sensor and an equally extraordinary lens, in many functional ways it is primitively point-and-shootish. There is no EVF or built-in viewfinder (although Sigma does offer an optional optical viewfinder which mounts on the camera’s hot shoe—about which, more later), so, minus the OVF, you must use the DP2M’s 3” LCD screen to compose and focus. Although the 30mm f2.8 lens is autofocus and there are a light on the top of the camera (near the hot shoe) and a bracket on the 920k-pixel LCD screen that illuminate when focus is locked, the speed of auto-focusing depends on how brightly or dimly the subject is lit. (While I wouldn’t say auto-focus is a bust with the DP2M, particularly in moderate-to-bright light, it certainly isn’t the speed demon that some DSLRs are, and in really low light it can do a good bit of hunting-and-pecking before locking focus.) That 920k-pixel LCD screen is adequate (at least when full sunlight isn’t falling on it), although it “swims” if the camera is moved (i.e., there is a lag before the LCD image settles back into crisp focus). There is no remote control (at this time) for the DP2M, although there is a self-timer setting in the Shooting Mode menu, with a user-selectable two-second or ten-second delay, for releasing the shutter when the camera is tripod-mounted. The shutter-release button on the top plate of the camera is a two-phase affair. You press it down “half-way” to meter and focus—both can be locked by pressing the AEL button if you choose to meter and focus on something that isn’t in the center of the frame and then “re-frame” (you can also change the focus/metering point on the LCD screen). You press the shutter button down all the way to snap the picture. It sounds simple and conventional, but I’ve noticed that if you don’t press the meter/focus/shutter button squarely in its center (or if the battery is getting low in charge), sometimes the camera won’t emit the little electronic beep it makes when focus/metering is locked or the electronic click “shutter sound” it makes when the shutter is fully depressed and you’ve taken the picture. On several occasions I’ve been uncertain whether I’ve actually snapped a photo because these noises didn’t sound (although in all instances properly exposed and focused pictures were, in fact, taken).

I mentioned battery life a sentence or two ago. With the DP2M it is truly dreadful. You will be very lucky if you get 50-75 images on a single fully charged battery. Happily, Sigma provides two BP-41 Li-ion batteries with the camera, but if you’re planning a whole day of shooting you had better stock up on spare fully-charged batteries.

Part of the reason why the batteries don’t last very long, beyond the fact that they are undersized and underpowered for this application, is the sheer amount of processing power images taken with the Foveon sensor require. In RAW mode (and, IMO and that of many other photographers, the DP2M must be shot in RAW mode to achieve the photographic quality it is capable of), a single Foveon-generated image comprises 45-50+MB of data (and that’s before post-processing). These are huge files and the speed with which the DP2M’s dual “TRUE II” processors write them is agonizingly slow. While the DP2M is equipped with a 7-shot buffer so you can keep shooting before these ungainly files are processed and written to your SD card, once the camera starts to write data to disk there can still be an appreciable lag before you’re able to take another photo, and after you reach the buffer’s 7-shot limit, you might as well order a Coke and ham sandwich to pass the time until the camera is ready to shoot again.

A camera that has no EVF or viewfinder, that uses a fixed focal length lens (not even a short zoom, mind you), that doesn’t focus particularly quickly even in great light, that is virtually unusable at high ISOs, that cannot be used at all if it is writing a file to your SD card, and that runs out of battery-power within 50-75 shots is scarcely a street-shooter’s dream. While carrying the DP2M around is easy (the thing weighs about a pound with battery and SD card installed), getting it to actually operate at the “decisive moment” is, at best, an iffy proposition and, at worst, an impossible one. This does not mean that the DP2M cannot be used as for street shooting (I will have more to say about this in the next paragraph), but what it does mean is that it is far better with stationary subjects in bright or controlled light (i.e., landscape, architecture, or formal portrait).

How do you turn the DP2M into a more efficient street-shooter? First, you buy the optical viewfinder, the Sigma VF-21, which is an extra $140-160. Second, if you’re trying to capture moving subjects (like people), you have to shoot in shutter-priority mode at a relatively high shutter speed or in aperture-priority mode at a relatively large aperture. (But, of course, you’d have to do this anyway with any camera.) Third, you should put the LCD screen into “Viewfinder Mode” (i.e., turning the LCD off via the Display button on the back of the camera). Turning off the LCD also goes a small (and I mean small) way toward better conserving battery life. Turning off the LCD (as a viewfinder) means you have to rely on the optical viewfinder for framing. Unfortunately, the Sigma VF-21 viewfinder, though perfectly usable, isn’t parallax-corrected and its white “frame lines” aren’t precisely matched to the DP2M’s 30mm lens; as a result, the OVF does not give you precisely the same framing you would get through the LCD screen (and the lens). In general, the image you shoot will turn out to be larger than what you see through the VF-21. Nonetheless, the difference in framing (and it is relatively slight) is compensated for by the convenience (and added physical support—the DP2M has no vibration control in its body or built into its lens) that OVF shooting gives you. Plus, once you get used to the OVF, you can reliably predict the slightly different coverage that the lens will record—and allow for it when you take the picture. It would be great if Sigma were to offer an EVF for this camera, but given the amount of extra power this would take away from its already sadly overmatched battery I kinda doubt that is going to happen. (If you’re wondering how you can tell whether the auto-focus is locked without glancing at the LCD screen, Sigma has, as noted, thoughtfully added a little light right next to the hot shoe (where the OVF mounts). Even with your eye to the viewfinder, it is easy to see when this light comes on; moreover, the camera emits a beep when focus is locked, making checking focus via the LCD screen unnecessary.) Fourth and finally, you will have to take your handheld street shots in daylight or by flash. Without a flash or a tripod, really low-light or night shooting is simply out of the question with the DP2M.

If you follow this advice will get you into the street-shooting ballpark, although nothing you can do will make the DP2M into an ideal moving-subject/action camera. The slow write-speeds and consequent delays between shutter activation alone make this impossible.

I’ve saved what might be the worst of the DP2M’s flaws for last, although the problem isn’t with the camera per se but with the imaging-processing software (called, with straight face, Sigma Photo Pro) that is supplied with the camera. To say that this software package is inadequate is putting it way too mildly. On my Mac, the names of the various tools are not only close to illegible but the entire program tends to freeze up and/or crash on a regular basis. Moreover, once you’ve figured out what’s what in the menus, the number of adjustments is limited—not even close to being the equal of full-fledged post-processors like Lightroom, Photoshop, or even Aperture.

So, you’re probably saying to yourself, why not just use Lightroom, Photoshop, or Aperture instead of SPP? Well…you can (and I do). But first you have to download those huge RAW files (coded in a format called X3F) from the camera, and at this point no third-party software supports the D2PM’s X3F files. To download Sigma X3F RAW files you have to use SPP and then convert them (in SPP) to 16-bit TIFFs, before opening those TIFFs in Lightroom, Photoshop, etc. for post-processing.

You may be wondering, at this point, why I’m spilling so much ink on what is, quite obviously, a camera of unusually narrow utility and multiple quirks. The answer is obvious: Within its many limits, the Sigma DP2M produces the highest-quality images I’ve ever seen from any digital camera. Indeed, it comes very close to the kind of color and detail I see in drum-scanned 4×5 sheet film—and I can’t say this about any other digital camera I’ve owned or used.

If you go to http://jlvalin.zenfolio.com/p743729886, you will find several examples (to which more are being added daily) of the output of the DP2M at various ISOs. You will also find several crops of these images, blown up not just 1:1 (as is customary) but 2:1, just to show you the kind of low-level detail this camera is able to record.

Here are some sample images. I’ve taken the following test shot with every camera I own—including the Mamiya 7 medium-format camera and my Toyoview 4×5 with Schneider optics.

Only drum-scanned images from the medium-format Mamiya 7 and the 4×5 Toyoview view camera have looked this true-to-life in color and this high in resolution. If you examine a 2:1 crop (200% enlargement) of this same image, you will begin to get an idea of just how remarkable this sensor/lens combo is.

Please note that neither of these images has been sharpened. This is simply the way they come out of the camera—time and time again.

As with hi-fi, one of the  effects of resolution and color fidelity that are this high is an increase in realism.

Objects and subjects imaged acquire what we hi-fi writers used to call “palpable presence.” They can also, as with hi-fi, acquire a characteristic three-dimensionality, which adds to this presence.

I’ve taken the test shot above with every camera I own and, once again, only the view camera would make this scene look so 3-D and reproduce the fellow in the lower left-hand corner—finishing his lunch on top of, or (alas) eating it out of a trash can—with this kind of clarity.

The parallel to world-class stereo equipment—to the way that extremely high resolution of color, detail, and texture fosters the impression of “being there”—is patent, although getting this kind of realism from such a compact, relatively affordable ($999) camera is quite unparalleled in high-end hi-fi.

I think I’ve made it plain that the Sigma DP2 Merrill is no panacea. It is a camera with all sorts of serious drawbacks. In sheer usability, virtually any other p&s, mirrorless, or DSLR will run rings around it. But in my experience no other camera, short of a 4×5 or a medium-format digital rig with a high-res back, has outdone it in image quality under the right circumstances. If you can live with its limitations, you simply can’t do better than this, IMO. 

ADDENDUM (11/03/12): Sigma has recently updated the firmware of the DP2M (version 1.02), improving auto-focus speed (even in moderately low iight). It has also updated Sigma Photo Pro (now version 5.4.0), although the improvements here don’t seem to make it any less clunky to use. There have been unconfirmed rumors that Sigma has given Adobe its X3F (RAW) file info, meaning that it is possible that we may see DP2M and DP1M RAW files supported in Lightroom and Photoshop. We’ll see.