Review: The Sigma DP2 Quattro

Normally, we  look at a camera from a holistic point of view and compare it to the competition or the class leader. This unfortunately doesn’t make sense for extreme outliers like the DP2Q; we’ll have to do something a bit different. This review will look primarily from the point of view of image quality, and whether we can live with everything else. This is the opposite from every other review I’ve written to date, and the reasons for this will become clear soon enough. The other big change will be considering workflow and software as part of the camera package: it’s impossible to do anything else, since unlike every other camera, there is no universal workflow we can apply. Those of you who do not like caveats, are unable to look at something objectively, or are not open minded, I suggest you save yourselves some angst and stop reading now.

16mm, anyone? Apologies for the camera shake: it’s very difficult to photograph yourself holding the camera in the actual grip but still being able to get your other camera-hand far away enough…

We will start in reverse: with image quality, because there are so many other compromises that this is really the only reason to even consider one of these cameras. Regular readers will know that my printmaster Wesley Wong is a big fan of the Sigma cameras; he loaned me the DP3 Merrill used in the earlier review here and has a full set of all five. Looking purely at the pixel level quality of the files, there is a good reason for this: under optimal conditions, these cameras put out some of the purest and highest-acuity pixels I’ve ever seen. They can go head to head with any medium format digital camera, and in the smaller format realm, only the D800E/ D810 combined with Zeiss Otuses can come close. Note first caveat: at the pixel level.

Toil

And here the problems start already: how many ‘pixels’ do these things really have? Ostensibly, native output size gives you 20M dots or thereabouts. SPP – Sigma Photo Pro, the de-facto conversion software – gives you a double size option that outputs about 80MP. I think that’s hugely optimistic, as at the pixel level things turn to mush; you lose the single-pixel detail that charachterizes all of Sigmas’ non-Bayer cameras to date. Working downwards from the 80MP file, I think equivalence is somewhere around the 33-38MP mark: the closest benchmark I can find is the D810, which sometimes outresolves it, sometimes not – depending on subject matter. If the Bayer algorithm plays nice with the subject, you’ve got more real pixels; if not, then you have interpolation losses.

Origin

Unlike the previous Merrill sensors, the Quattro does have interpolation; we used to have RGB values at each indivdual photosite, but now we have 20M blue photosites stacked on top of a further 5M red ones and 5M green ones; Sigma claims 39MP equivalent resolution, and I think they’re not far off. However the idea of equivalency is somewhat nebuluous: with AA filter, or without? What quality of lenses? From the middle, or the edges? Etc. Second caveat: in practice, I find that under optimal conditions, the whole single capture resolution of the Quattros to be more or less the same as the D810 and an excellent lens – say Nikon PCE or stopped down prime. If we put an Otus, APO-Sonnar or APO-Lanthar on, things swing in favor of the D810. But it is worth noting that the matched lens-sensor pairing is really the way to go when it comes to optimizing performance and size; the GR and Coolpix A are great examples of this; as is the fact that all normal lenses of similar performance for the D810 are quite a bit larger than the Quattro, let alone the Quattro’s lens.

First of a series of examples; DP2Q at left, D810 with 45PCE at right. Shot at base ISO for both cameras and f5.6 for the Sigma, F8 for the D810 to compensate for the different formats. At these sizes, the DP2Q appears to have more detail – because it certainly has blockier microcontrast. Neither camera has been sharpened; the DP2Q file was saved as the ‘double size’/ 80MP option in SPP 6.2, then downsized to match the D810 in PS CC. But look again at 100% example 1; example 2; example 3; example 4. They are from the same pair of images but different portions of the frame to rule out lens advantages. Not so straightforward, is it? Remember that you’re looking at the very best case scenario: timer/MLU/EFC on a solid tripod, optimal apertures, optimal focus, base ISO. The real world handheld isn’t quite as good.

The advantage is not always quite so clear cut, however: it’s worth noting that the multilayer architecture of the Quattro sensor means that its color accuracy is noticeably better than any Bayer camera; it doesn’t suffer from odd clipping or tonal inaccuracy in only very slightly saturated areas. It also doesn’t have artefacts in areas of high chromatic frequency where luminance is relatively similar. It also means that you can get a relatively clean ~20MP B&W file out of it at high ISOs using only the blue (top) layer; there’s much less noise since there’s also less amplification of the signal required for not having to pass through the other layers of sensor.

Inclination

Those of you who were paying attention will have noticed the ‘optimal conditions’ limitation. The [shooting envelope] of this camera is very, very small indeed. Expect something of the order of the previous generation of CCD-based medium format cameras, and you won’t be disappointed. If you buy a Quattro expecting comparable usability to other large-sensor fixed-lens compacts like the GR or X100T, you’re going to be very disappointed indeed. The Quattro’s limitations are both what I think of as implementation-driven (AF speed and battery life mainly) and sensor-driven (limited high ISO capability, workflow). If you use the Quattro on a tripod at base ISO, the output will blow you away. If you try to do low light documentary, you will probably find an iPhone to be a much better tool and deliver better results.

Stool

This is where things get ugly: despite another generation of evolution of body design, it seems Sigma have not gotten many things right. For one, the design is nearly impossible to hold in any ergonomic fashion. It is more hand-unfriendly than even the Df, but at least it isn’t as heavy. I cannot honestly figure out how to hold it in landscape orientation. In portrait orientation, I use my left hand underneath like one of those old cine cameras; the LCD hood comes in useful as face bracing for stability. Button placement leaves me scratching my head, too – no matter how I put my right hand, the first button that falls to thumb is always the display mode settings – it should really be programmable AE-L or quick settings since both of those are more frequently used. And what were they thinking by putting the SD card slot under a flimsy rubber tethered cover? Hmmm.

Planarity

Then we have AF speed: in good, bright light – it’s barely on the side of fast enough and noticeably better than what I remember of the Merrills; once you get into typical indoors-at-night territory, you’d better either be prepared to wait for some time for focus to lock, or take your chances with manual. The live view gets pretty grainy and coarse, too – which makes it even harder to focus or determine if the camera has nailed it or not. I could see decoupling AF to one of the back buttons being a viable solution, but I couldn’t find any way of disabling shutter-AF, either. I suppose it’s indirectly a good thing that ISO 800 is only usable in an emergency (1600 for blue-channel B&W); anything darker needs a tripod and means you won’t miss fast focusing anyway.

Untitled

We then have battery life. The Merrills were notoriously power-hungry; I’m pretty disciplined about power use, but never managed more than 100 shots per charge on one of those. Sigma claims that the Quattros double that; probably because the battery itself is double the capacity. Nevertheless, I’m still wary when a camera includes two batteries in the box (are you taking note, Sony? If battery life is going to be poor, at least acknowledge it instead of taking advantage and extorting you for a spare). It seems power consumption is really linked to runtime and nothing else: if I leave the camera on but take only a few shots, I’m dead in about 45 minutes. If I power on only for the shot, I’ve been able to squeeze out 300 images per charge. But I do really feel like the camera has me under time pressure; much the same as the A7II did. Fortunately, the external charger is pretty fast, and official spares are relatively cheap at $30 each.

Irregularity

Let’s not even talk about SPP: whilst the software is much better than the earlier versions I’ve used, it’s still extremely slow even on a machine with plenty of ram that can handle changes to large 50MP Bayer files in real time. It’s also not very intuitive. One surprising omission is the ability to do any sort of color profiling of indivdual HSL channels; either that or they’re hidden in such a nonintuitve place that they might as well not have been included at all. There’s one other thing I’ve not been able to figure out: why the initial instant preview looks so different to what comes out after the converter has finished rendering.

Obligatory cat

Batch processing is painful (and you really need to treat each file individually, because there isn’t a blanket set of adjustments that works in general) and the response of various sliders doesn’t seem consistent – ‘Exposure’, for instance has very little effect except for large motions, but ‘X3 Fill light’ seems to vary wildly with just a small portion of that slider’s total motion. Overall, it’s about the worst workflow I’ve ever experienced: even after taking on average five minutes to output a flat TIFF file to work with, I still have to run it through ACR and PS to get the output I want. And no, there’s no easy way to get to a final output file using SPP only. There are just too many intermediate workflow steps involved to get to ideal output – clearly, this is not a camera for prolific shooters. It is worth mentioning that their B&W conversions actually produce very good results; whether this is a consequence of the sensor architecture or the software routines isn’t clear, however – and there’s no easy way of finding out, either.

Stool shadow

Sigma does deserve credit for doing some things very, very right though: the LCD magnifying hood is a perfect solution to stability, daylight visibility of the screen, checking focus, and not having to add the cost or power drain of an EVF. The hood has a portion that screws into the tripod mount (but leaves you another mount hole), sits flush with the camera, and allows the magnifier itself to slide in from the side; it’s secure yet easily detachable if necessary. Both pieces are very, very well made; the diopter adjustment is possibly the most precise and elaborate I’ve seen, and even the eyepiece cap is machined aluminum. It really feels like a rigid single piece when installed – which is good, because your left hand is going to be using it a lot to grab the camera with.

Overall build quality is really excellent, and the camera feels solid in the hand. The menus and electronic portion of the camera is responsive, well thought out, and only has a couple of minor omissions – the ability to set lower auto-ISO thresholds, and exposure value increments. Shutter response time is instant, but it’s a shame that shot to shot time is not – though the camera does have a 7-shot buffer, it takes a few moments after capture for it to go back to being able to record again, and a surprising amount of time to record even with a 95MB/S UHS I card.

Urban Mondrian

I have a theory about battery life and design. It’s clear that the sensor is indeed very power hungry; the amount of heat being dissipated through the front of the camera is considerable. After half an hour or so of shooting outdoors in the tropics, the camera verges on the threshold of uncomfortably warm across its entire front surface, even the lens mount. This necessitates a lot of surface area to radiate the waste heat, otherwise you might land up with even more noise problems – and something physically dangerous. It does not, however, explain the very odd grip shape. Just rounding off that front edge would have made an enormous difference in feel and ergonomics. I suppose all of this amounts to making the Quattro a very good studio camera – use it at base ISO on a tripod where you don’t have to carry it, plugged into an AC adaptor where you don’t have to worry about power, and then use the 1/2000s leaf shutter to sync to your heart’s content.

Vehiclular camouflage

No doubt then, there are a lot of promises and a lot of compromises. Under ideal conditions, the image quality of these cameras still remains superb: there is nothing at this size and price that can touch them resolution-wise; there is very little that can come close in color accuracy at any price, and not without significant postprocessing effort. The bottom line is that the files are really quite addictive, and also have quite a bit of dynamic range and postprocesisng latitude. That said, when either end of the tonal scale goes, it doesn’t go in a nice way: highlights can clip a little abruptly, and shadows get noisy/ gritty/ muddy. But in every case, I’ve found there’s a lot more dynamic range than what I see on the back LCD would suggest.

A window beyond

Sadly though, the multiple layers of the sensor still mean that the red and green photosites on the lower levels still have to be amplified considerably; noise above ISO 400 starts to become noticeable, objectionable past ISO 800, and unusable except for blue-channel only monochrome at 1600. Frankly, I’m not sure why they bothered offering 3200 and 6400; they look like selective color filters. It isn’t the amount of noise that’s actually objectionable; it’s the very strange nature of it that is no doubt due to a combination of interpolation, a very clever noise reduction algorithm, and strange things that happen (color blotchiness, mass tonal shifts in certain areas, nonlinear highlight/shadow behavior) when you amplify the different color channels at different strengths. I would basically shoot this thing at base ISO, or perhaps up to 400 in a pinch. Beyond that, you’re giving away a lot in image quality; I’d actually say an E-M1 image looks better from somewhere between ISO 800 and ISO 1600. The D810 starts pulling away at 400 and above.

Trees without trees

One important final point to note: whilst the lens of the DP2Q is excellent, an a very good match for the sensor, and it handles shooting into the light just fine – the sensor does not. There is some rather spectacular flare or internal reflection or interaction between the layers of the sensor that mean you cannot really have a bright point source in the outer edges of your frame without some seriously bad (and very obvious, because it’s usually bright green) flare. If the source then moves to the center portion, the problem mostly goes away. Not a deal breaker, but it can be quite annoying if like me you like your sunstars and backlighting.

Strange flare: the green cast in the lower portion of the frame is caused by the sun at top right.

It is quite difficult to come to any sort of definitive conclusion on the Quattro: it somehow manages to be a polarizing camera even relative to itself. It really has no competition other than its predecessors; anything about the same size/volume has much lower image quality. Anything with the same image quality is significantly larger and more expensive. If you want the best possible image quality, but on a budget: this is the way to go. Or rather, a set of three would be the way to go. You may however want to try the Merrills first: they’re more ergonomically friendly, optimal image quality isn’t really that different*, and with a little legwork, they’re also half the price. (You do lose the ability to attach the LCD hood, though, and battery life is 1:3 in practice.) Personally, I thought it made a very good ‘urban sketch’ or ‘urban painting’ camera – small enough to be unobtrusive, high enough quality to Ultraprint if desired. The ergonomics weren’t quite as much of a headache as I expected, though they’re far from optimal; what was an issue was the really slow workflow. You could I suppose just shoot JPEG, but that’s leaving most of the file quality behind. I can’t help but feel the DP2Q is another near miss: sort out the grip, give it ACR support, and we can forgive the limitations of the sensor simply because of what it can do.

*And there are a lot of convincing, scientific tests I’ve seen online that suggest the Merrills may actually deliver better results under some specific situations because they do not require any interpolation and deliver true RGB values for each photosite.

Urban Rothko

In the end, it’s going to boil down to whether your priorities are image quality and price, or versatility and price, or image quality and versatility with no consideration to price. That basically makes the options Sigma, other mirrorless, and D810-based. Remember that if you need another focal length with matching image quality, you’re going to have to buy another whole camera. And there are only 21-45-75mm-e options; anything else will require adaptors and the associated lowering of image quality. I’m not sure even a set of Quattros or Merrills is going to be flexible enough to be your only system unless perhaps you have very limited and specific shooting needs; most photographers are going to be better served by versatility. But I can see the appeal of adding one to cover your most frequently used focal length in a very high quality and relatively compact/ affordable way; what I can’t answer is whether any of the camera’s limitations or ergonomic flaws are going to be deal breakers for a particular individual. Perhaps my thoughts on the Quattro are best summed up this way: better than the Merrills, for every situation I’ve encountered, yes; D810 and medium format owners can safely pass; everybody else, look at the files first and then decide – better yet, try to convert some raw files yourself. There really is something seductive about this level of image quality. MT

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The Sigma Quattro is available here from B&H in 28mm-e DP1Q or 45mm-DP2Q flavours, along with the LVF-01 LCD hood and spare batteries.

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