We kicked-off this review by describing the DP1 as the most highly anticipated compact camera around, and that’s not just because Sigma’s kept us waiting since announcing it back in 2006. It’s because the DP1 represents what enthusiasts have desired for much, much longer: a compact with a DSLR sensor.

Commenting from the sidelines it seems such an obvious solution. As resolutions increase, the tiny sensor real estate on compact cameras has become ever-compromised, resulting in noise and processing artefacts even at their lowest sensitivities. So why bother with a small sensor at all? Simply fit a nice large sensor like you’d find in a DSLR in a premium compact and bingo, low noise at high sensitivities and a decent dynamic range to boot. Sure, the bigger sensor would increase the cost, but it’s something most enthusiasts would happily pay for on a top-end model.

Clearly it’s not that simple (or lucrative) though as no manufacturer other than Sigma has decided to do anything about it. The only thing that’s come close to date was Sony’s Cyber-shot DSC-R1 which housed a DSLR-sized sensor in a non-DSLR body, but it remained a large camera. The Sigma DP1 is the first and so far only truly compact camera to house a DSLR-sized sensor.

This alone should be cause for celebration and Sigma commended for boldly going where no manufacturer has gone before, but there’s trouble in paradise. Sigma describes the DP1 as ‘a compact camera with all the power of a DSLR’, but this statement should come with a long list of caveats.

But first, the good news. Set to 100 or 200 ISO, the DP1 can capture an astonishing degree of detail per pixel. Don’t be fooled by the relatively low output resolution of 4.69 Megapixels – as you’ll see on our results pages, the DP1’s images contain essentially the same amount of fine detail as a 12 Megapixel DSLR. And unlike most DSLR kit lenses, the DP1’s excellent optics maintain sharpness across the entire frame to deliver images which are literally packed with detail. The Foveon X3 sensor also delivers a unique look of its own with images which jump out at you.

Then there’s the manual control. The DP1 offers full control over the aperture and shutter, and thanks to its larger sensor and actual focal length, you can easily achieve a smaller depth of field than a compact. The manual focusing is also pretty good.

Detailed images, sharp lens and manual control – sounds great so far, right? Well it is, but now for those caveats. We hoped that having a DSLR-sized sensor would allow the DP1 to deliver DSLR-type quality at higher sensitivities. Sadly not. While the output at 400 and 800 ISO is considerably superior to modern compacts, it’s marred by significant chroma noise that’s below what you’d expect from a DSLR. And strangely 800 ISO is where the DP1 stops, not bothering to offer 1600, let alone 3200 ISO.

Further reducing its suitability as a low light camera is the screen, which in dimmer conditions grows noisier and loses colour until the live image becomes monochrome. Of course the picture it subsequently records is in colour, but we’ve not seen any decent digital camera suffer like this for a long time.

Next is handling. Sigma describes the DP1 as having ‘all the power of a DSLR’, but we don’t know of any DSLR which takes four seconds to power up, as long as two seconds to autofocus in decent light and five seconds to record an image before being ready for action again.

It sounds like a visual gag from a cartoon, but we were taking a photo of a vintage steam roller crawling past at a country fair using the DP1 and actually found it had moved out of view by the time the camera was ready to take a second shot. You could of course use the continuous mode which can fire a burst of three frames in one second, but by subsequently tying up the camera for over ten seconds following the burst, you’d better hope to have got the photo in those three.

So the DP1 isn’t a low light camera. Nor one you’d use to capture subjects in a hurry or any motion unless you’re sure you’ll get it right first time or in a burst of three. Both are aspects in which a DSLR excels. So the DP1 only really has the power of a DSLR in terms of sensor size and manual control. So how does it measure-up against a compact? The image quality is better, but what about the technological luxuries we’ve become used to?

Well you already know there’s no optical zoom nor any image stabilisation. The QVGA movie mode is a step back from the common VGA standard, let alone the increasing number of HD options becoming available. The screen is an average 2.5in model which goes black and white in dim light – you don’t get that with decent compacts these days. Suffice it to say there’s also no face detection nor any scene presets or a foolproof auto mode. Of greater concern is the lack of quick access to popular settings, a live histogram or the ability to record RAW and JPEG files at the same time.

Of course the DP1 isn’t designed to compete on such features, but when using it you do realise how many you’ve become used-to on a modern compact. And like most luxuries, while they’re not strictly necessary, they are certainly nice to have.

This all puts the DP1 in an uncomfortable position when it comes to comparisons. It’s neither quick nor good enough in low light to go up against a DSLR, and it’s feature-set is basic against a modern compact, while also being much more expensive. But in the absence of anything else, that’s what we’re going to compare it against here: the smallest DSLR on the market and two high-end compacts.

Compared to Olympus E-420

The Olympus E-420 may be the world’s smallest and lightest DSLR, but even when equipped with the diminutive 25mm pancake lens, it’s clearly a much bigger camera than the DP1. You can see both cameras side by side on our design page. It’s unsurprisingly heavier too at 521g with battery and 25mm lens. The E-420 can just about squeeze into larger coat pockets with a subsequent bulge, but the DP1 will slip-in with ease. So in terms of size and weight, the DP1 of course wins here.

Beyond size and weight, the DP1 also boasts a movie mode, albeit basic at 320×240 pixels, and the unique picture quality of the Foveon X3 sensor which subjectively may be preferable. Again, don’t let the DP1’s relatively low output resolution of 4.69 Megapixels fool you as it can keep up with 10 Megapixel DSLRs in terms of detail.

In almost every other respect though the E-420 is a more powerful and better-featured camera. It has interchangeable lenses, much faster handling, the choice of composition with an optical SLR viewfinder or the screen, a slightly larger 2.7in monitor, support for more powerful external flashguns, a live histogram, quicker access to settings, and better performance at higher sensitivities. The list goes on.

In terms of pricing, the E-420 when bundled with the 25mm pancake lens is actually slightly cheaper too, and the gap widens further if you opt for the 14-42mm zoom kit, although this of course makes the camera bigger. So as you’d expect, you’re weighing-up the DP1’s portability and imaging style against the E-420’s power and flexibility. See our Olympus E-420 review for more details.

Compared to Canon PowerShot G9

Until the DP1 came along, the PowerShot G9 represented one of the best choices for a demanding enthusiast who wanted a powerful compact camera. The Sigma DP1 however beats it in several key respects: the lens may be fixed, but it’s wider and sharper, the body is smaller and a little lighter, and crucially the DP1’s sensor boasts over 7.5 times the surface area.

If you compare our Canon G9 Gallery against our Sigma DP1 Gallery, you’ll notice there’s noise and processing artefacts on the former even at 100 ISO. This is absent on the DP1 until you reach 400 ISO, but even then the output remains superior. Interestingly we’d say there’s not as much in it at 800 ISO though and in some respects the G9 is actually preferable. It should also be noted the G9’s images contain 12 Megapixels to the DP1’s 4.69 Megapixels, so by downscaling the former, or upscaling the latter, the differences will reduce. But even then at 100 and 200 ISO, the DP1 is hard to beat.

Beyond size, weight and image quality at lower sensitivities though, the G9 comfortably takes the lead. It features a 6x optical zoom lens with image stabilisation, a brighter focal ratio when zoomed-out, an excellent macro mode and optional extenders, a bigger and brighter screen with face detection and a live histogram, quicker handling, an optical viewfinder as standard, support for more powerful external flashguns, better quality VGA movies with a time-lapse feature, and an optional underwater housing.

So this time it’s a case of comparing the DP1’s superb quality at low sensitivities and slightly smaller size against the G9’s more powerful feature-set and cheaper price, which at the time of writing was comfortably lower. See our Canon PowerShot G9 review for more details.

Compared to Panasonic Lumix DMC-FX500

Our last comparison is against a different kind of high-end compact. The Lumix FX500 is the flagship model from Panasonic, but offers a more gadgetry approach. The key advantages of the DP1 of course remain: a fixed but well-corrected lens and a sensor which this time boasts over ten times the surface area. The DP1 also features a flash hotshoe.

So open our Sigma DP1 Gallery and our Panasonic FX500 Gallery to see the difference this makes in practice. You’ll immediately see the FX500 exhibiting noise and processing artefacts even at 100 ISO, and the DP1 capturing cleaner, detailed images even with its lower output resolution. We directly compared the DP1 against the FX500 in our results and outdoor noise pages too, so take a look and see what you think. And while the DP1 deteriorates at 400 and 800 ISO, it remains superior to the FX500 even when the images are scaled to match.

The DP1 may be small and light compared to a DSLR, but the FX500 is smaller and lighter still – you can see the difference on our Design page. The FX500 also features a 5x optical zoom lens which starts wider and ends much longer, while additionally offering image stabilisation, a bigger screen with touch-sensitive controls, High Definition video recording with optional HD output, scene presets and a great auto mode, quicker handling, a live histogram, face detection, and it’s also almost half the price.

So this time it’s a case of comparing the DP1’s superb quality, especially at low sensitivities against the FX500’s more luxurious feature-set and much cheaper price. See our Panasonic Lumix DMC-FX500 review for more details.

Sigma DP1 final verdict

The Sigma DP1 is certainly a unique camera and once again achieves the important goal of equipping a compact body with a DSLR-sized sensor. Use the camera in the right conditions and it really shines, delivering images with an astonishing degree of detail and sharpness across the entire frame.

Sigma should also be commended not just for developing the camera that no-one else wanted to, but also for supporting it with a steady stream of firmware updates which actually addressed several early criticisms we had of the camera while still writing the review. No grid? Fixed with v1.01. No shooting information with the grid? Fixed with v1.03. Live Histogram and RAW plus JPEG shooting? Fingers crossed for the future…

But the downsides to the DP1 are considerable to say the least. With the big sensor and sharp lens, it seems almost churlish to complain about the lack of features you’d expect from a modern compact, so we won’t mention them again here. But the excruciatingly slow handling and poor performance in low light are significant disappointments, especially the latter considering the sensor size and pixel density. Indeed they’re deal breakers if you need a camera that responds quickly or works well in darker conditions. Couple these with the high price and other issues described above and it misses out on our broad Recommendation to a general consumer.

But again the DP1 is not designed for a typical camera buyer. It has key advantages in very specific conditions and if they match your style of photography, you won’t be disappointed. If you’re into action or sports photography, group shots of people or decent low light performance, we’d say forget the DP1. But if you take a slower, more considered approach to your photography, shoot subjects in daylight which are generally static like landscapes or buildings, and can stick to the lower sensitivities, then the DP1 can be a superb tool, capturing an enormous degree of detail with a unique style of colour and tone.

If that sounds like you and you’re unable or unwilling to carry a DSLR, then the DP1 is worth considering. As for anyone else who wants a feature-packed compact with a big sensor to deliver DSLR-like image quality, the search remains. If Sigma believes it’s worth the investment, then maybe the DP1’s successor will be closer to satisfying a larger audience, or perhaps companies like Canon will finally see the value (and find some technical means) in equipping a model like the G9 with a bigger sensor.

The perfect enthusiast’s compact continues to elude us, but we remain hopeful for the future. At least one company has made the important first step of using a bigger sensor and in a smaller form factor and for that we thank you Sigma.