There are 7 ISO settings available on the Sigma sd Quattro for both JPEGs and RAW files. Here are some 100% crops which show the noise levels for each ISO setting, with JPEG on the left and RAW on the right: As the Sigma Quattro stills are so detailed at 1:1, the 5K results can easily be upscaled to compete with the monstrous Sony 42MP bayer sensor in the A7R II, RX1 II and A99 II.

The sd Quatro H has a new option which helps open possibilities: DNG files. All of us using raw file editing programs can rejoice and not have to worry about conversions. However, the format has a lower bit depth than the .X3F format. Foveon purists may be concerned about the color resolution that the Quattro design gives up, but in practise it's able to give ground on that front and still deliver images that are distinctly un-Bayer-like in their appearance. And, since Bayer sensor output is what most people think of, when they think about digital photography, this is something akin to saying distinctly un-digital. As with all Foveon chips, the sensor interprets color based on the fact that different colors of light have different amounts of energy and so can penetrate the sensor to different depths. This is radically different from conventional designs that place filters in front of the sensor, throwing away around half of all the light so that each pixel only 'sees' light of a predetermined color.That's how long it's been since the release of the SD9, Sigma's first digital camera, which was also the first camera to use the layered Foveon sensor design. From then on, for better or for worse, Sigma has continued to refine its unique layered sensors. While no one will argue that their cameras are capable of insanely sharp output, you still have to put up with an awful lot of shortcomings. The Sigma sd Quattro offers a full range of advanced exposure controls via the Mode button on the rear of the camera, including aperture-priority, shutter-priority, manual and manual focusing, with three Custom modes so that you can save and recall your preferred settings. There are no auto-everything or scene modes on this camera, which is a veritable breath of fresh air at a time when most manufacturers are stuffing their cameras full of clever technologies that take control away from the user. The aperture or shutter speed are set by using the forefinger-operated control dial on top of the camera which encircles the shutter button, with a smaller rear control dial setting the aperture in the Manual shooting mode and exposure compensation in the other modes. The Sigma sd Quattro H camera is a mixed bag with a specific audience. They have made strides in shooting speed and buffering over time (the first iterations of their Foveon sensor cameras were quite slow, almost to the point of uselessness) and that has helped bring up overall usefulness. The following were shot with the Hoya Infrared (R72) visible light cut filter on the Sigma 18-35mm lens. This cuts visible light and only allows through infrared.

The Quattro H is able to shoot very detailed images with a distinctly different way of rendering the finest detail. It's this that has won Foveon such a loyal fan base. Unlike previous Foveon chips, the Quattro design doesn't attempt to capture full color information at every pixel, instead capturing more spatial resolution than color resolution. This is a fundamentally similar trade-off made by conventional sensors, so it'll be interesting to see whether this latest design can maintain enough of what made Foveon distinctive while trying to offer more competitive results in other respects. While the SD Quattro’s dynamic range appears to be not as good as the latest Nikon or Sony cameras, the camera has a Super-Fine Detail (SFD) exposure mode which basically shoot seven photos each at different exposure and the results are combined together as a huge X3I format file. (7 x normal raw file size) This mode is used to improve the dynamic range and also minimise the image noise. Downside of the SFD mode is that you pretty much have to use a tripod and you might also end up having some weird results when shooting a scene with moving objects. If you are a sports photographer, or photojournalist that shoots under various light condition, or parents that love taking photos of your little kids, this is not the camera you are looking for.It is the build quality and grip size that sets the SD Quattro apart from the Sony’s and Panasonic’s mirrorless fleet. In just a couple of years, Sigma have gone from frustration tear-inducingly slow Foveon sensor and very long processing times on cameras like the DP2 Merrill, to a sweeping improvement across the board with regards to how responsive the Quattro range is. Foveon is sitting pretty for the future. But stop. Have I gone mad?

The live-view mode is rather pixilated and although the EVF glass and panel are high specced, the overall EVF experience suffers from the lower resolution live-view feed too. Colour isn’t just down to the sensor of course, a lot goes on in the processing and de-bayering. Canon and Fujifilm do an aesthetically beautiful job of this, whereas Sony tend to go for a more technically precise put perhaps less pleasing end result. I do struggle with Sony cameras sometimes to put skintones in a more flattering, less clinical place – not just with S-LOG but with the raw stills too. How it works

Before we get to the downsides of the Sigma sd Quattro H, let’s cover what it does so very, very well; details. The sensor has a dynamic range of slightly less than 10-stops, giving pause to those accustomed to the growing dynamic range of most modern DSLR cameras. That said, landscape shooting does tend to reward a patient approach to picture taking, so neither this need to take extra care, nor the considerable delay as the camera writes its huge DNGs were of particular concern. We suspect most people will be happy enough with the image quality to overcome the occasional hurdle placed in your path. Sometimes my eyes don’t seem to see straight, so I found the onscreen level to be very handy. It can be turned off for those who don’t want it, but for the rest of us, it’s quite useful.