Canon EOS 5Ds review

Three years ago we got dewy eyed about the Canon EOS 5D Mark III, a full-frame SLR that scored straight As for image quality, features and performance. A lot has happened since then, though, not least the arrival of the Nikon D750. The two cameras are closely matched for image quality, performance and features, but the D750 has a tilting screen, Wi-Fi and costs just £1500. If there's one thing more alluring than a full-frame SLR, it's a full-frame SLR with a superb lens attached. A cheaper body means more cash to spend on glass.

Canon has hit back with the EOS 5Ds, which comes fitted with a 50-megapixel sensor – the highest resolution to date for a full-frame SLR. This equates to 8,688x5,792, which is enough for A1 prints at 250dpi. There can't be many photographers who feel the need to print at such large sizes, but there's something reassuring about never having to worry that your images aren't detailed enough. 50 megapixels are great for large group portraits – perhaps at weddings – so you can zoom in to see people's faces. It allows judicious use of the crop tool while still maintaining plenty of detail. It's also worth noting that a sensor's output is always crisper after it's been resized downwards, due to the way colour sensors handle anti-aliasing and only record red, green or blue colour channels at each pixel. A 50-megapixel sensor should produce crisper 24-megapixel photos than a 24-megapixel sensor.

It's not enough just to pack lots of pixels onto a sensor, though. The rest of the camera has to deliver to the same degree. There's some encouraging attention to detail that demonstrates Canon's commitment to the cause. The press release refers to a reinforced chassis, baseplate and tripod lug to improve rigidity. The mirror flip-up mechanism has been redesigned and it's possible to add a fixed delay of between 1/8 and two seconds between mirror lock and shutter release. All of this should help to reduce vibrations when shooting with a tripod.

There's no shortage of superb Canon EF lenses to choose from, and I'd expect them to live up to the demands of this sensor. The 50-megapixel full-frame sensor has the same pixel density as a 20-megapixel APS-C sensor, so this sensor requires a similar level of lens sharpness as the current generation of 24-megapixel cropped-sensor SLRs.

The same could be argued of the demands placed on autofocus, but this is an area where cropped-sensor SLRs can struggle to deliver pixel-perfect results. The 5Ds is fitted with the same 61-point autofocus sensor as the 5D Mark III and the flagship EOS 1D X. It's a dense array of points, and 41 of them are cross-type for increased sensitivity. When shooting with an f/2.8 or brighter lens, the central column of five points are dual-cross-type for extremely accurate focusing.

Meanwhile, the 5Ds's metering has been upgraded compared to the 5D Mark III, with a 150,000-pixel sensor that measures red, green, blue and infrared colour channels. It's a big step up from the Mark III's 63-zone metering sensor, and should lead not only to improved metering but also superior subject tracking for autofocus. In my tests, the 5Ds's subject tracking was good but not brilliant. We didn't have both cameras to compare directly but our recollection is that the Nikon D750's tracking mode was more reliable.

Sharp photos also depend on a suitable shutter speed. It might be reasonable to assume that anyone considering a £3,000 camera knows how to manage exposure settings, but I still prefer a camera that makes intelligent decisions without intervention. The 5Ds's Auto ISO mode is more customisable than before. The minimum shutter speed can be set manually or left to be adjusted dynamically depending on the focal length. Unlike on the 5D Mark III, it's possible to shift these dynamic speeds towards slower or faster values. However, the Auto ISO setting doesn't respond to motion of the subject or camera. For moving subjects it's essential to set the shutter or ISO speed manually.

With a bigger sensor comes higher demands on data management. Files are about twice the size as the 5D Mark III's, with JPEGs varying from 10 to 30MB depending on the complexity of the scene and RAW files weighing in at around 55MB. Higher-resolution sensors (and their processing needs) tend to draw more power, and sure enough, battery life has fallen from 950 to 700 shots.

Continuous performance also takes a hit, although the move to a faster processor means it's not as drastic as it could have been. While the 5D Mark III shoots at 6fps, the 5Ds manages 5fps. It slowed after 43 JPEGs to 3.1fps when testing with an SDHC card (rated at 94MB/s), but continued for over 100 JPEGs when testing with a CompactFlash card (rated at 90MB/s). RAW continuous shooting lasted for 18 frames before slowing to around 2fps.

Ergonomics and video

Otherwise, the 5Ds is virtually identical to the 5D Mark III. That's by no means a criticism as far as ergonomics are concerned. The curved magnesium alloy shell feels extremely sturdy and comfortable to hold. There's a strip of buttons along the top plate that reassign the command dial and rear wheel to various functions. With all of these settings plus autofocus and exposure relayed through the viewfinder, there's rarely any need to take your eye from the viewfinder while shooting.

The viewfinder's 0.71x magnification gives a big, detailed preview of the scene that makes composing shots a real pleasure. It's not necessarily big enough for pixel-accurate manual focus adjustment, though. For this it's better to switch to live view on the 3.2in screen, with the option to magnify the preview by up to 16x.

The headline video specifications are unchanged, with 1080p capture at 24, 25 and 30fps in AVC format, plus an All-Intra codec that virtually eliminates compression artefacts with its 90Mbit/s bit rate. However, will all that processing power on board it's disappointing not to find 4K video capture, or even 1080p at 50fps.

At least video autofocus has been upgraded from the chugs and jitters displayed by the 5D Mark III. However, only two of Canon's STM range of lenses – designed for smoother performance for video – are compatible with full-frame SLRs. The 5Ds loses a couple of video-related features compared to the Mark III. There's no headphone out, presumably due to the move to a larger USB 3 socket, and the HDMI output can't send a clean feed to an external monitor or recorder.

Image quality

I've long admired EOS cameras' JPEG output, with a colour palette that strikes a sublime balance between accuracy and flattery, and the 5Ds is no exception. Automatic exposures were expertly balanced, and I rarely felt the need to reach for the exposure compensation dial.

This camera is all about detail, and the majority of shots had it in abundance. There were times when camera shake, focusing errors or subject motion took the edge off, but given the number of things that can compromise detail levels, it's reassuring that sensor resolution isn't ever likely to be the weak point in the chain.

The downside is that noise levels are higher than from the EOS 5D Mark III and other modern full-frame cameras. The difference was noticeable at ISO 800 and more significant at ISO 3200 and above. However, comparing photos at 1:1 pixel magnification isn't a fair test. Comparing their output at similar overall sizes, the difference was much subtler. Personally, I struggle to get excited about the increased resolution but I'm not particularly worried about the increased noise, either. This is a modern full-frame digital SLR and image quality is as high as I'd expect.

^ Canon's usual flair for vibrant JPEGs is evident here, and there's enough detail for gargantuan prints. (1/200s, f/10, ISO 100, 40mm equivalent)

^ The wall texture at the centre of this shot is exceptionally sharp. The edges of the frame are slightly less so. If a lens has limitations, this camera will find them. (1/160s, f/8, ISO 100, 20mm equivalent)

^ These dense, subtle textures are handled superbly by the JPEG engine. The exposure is well judged, too, keeping the sky and shadows just short of clipping. (1/200s, f/10, ISO 100, 23mm equivalent)

^ 50 megapixels are enough to pick up every pore and strand of hair. (1/200s, f/4.5, ISO 100, 176mm equivalent)

^ Autofocus wasn't always as reliable as we'd hope for. This shot (and a few others in my tests) has front-focused. (1/400s, f/4, ISO 1250, 191mm equivalent)

^ A major advantage of the 50-megapixel sensor is the ability to apply substantial crops and still have plenty of pixels to play with. (1/160s, f/9, ISO 100, 40mm equivalent)

^ This crop is of the above frame is 7 megapixels – still enough for an A4 print.

^ The downside of 50 megapixels is that pixel-sharp focus can be elusive. (1/400s, f/4, ISO 2500, 200mm equivalent)

^ Noise is understated at ISO 1000 but close inspection reveals some grain, especially in out-of-focus areas. (1/80s, f/4, ISO 1000, 70mm equivalent)

^ By ISO 3200 it's quite pronounced – on close inspection at least. (1/400s, f/4, ISO 3200, 200mm equivalent)

^ Per-pixel noise is on a par with cropped-sensor SLRs, but with so many pixels available, even ISO 6400 is easily good enough to print at modest sizes. (1/5s, f/4, ISO 6400, 35mm equivalent)

Recipe for success?

Those who have been waiting expectantly for an EOS camera with 4K video recording (and which costs less than the £6,000 EOS-1D C) will have to keep waiting. The 5Ds is a stills camera with few incentives for videographers. That's perfectly reasonable, but I can't help thinking that Canon could have come up with a little more in the three years since the 5D Mark III. The new sensor will be welcome for some people but fairly irrelevant for many. They may as well stick with the Canon 5D Mark III, which remains on sale for around £2,250.

I'd have liked the 5Ds to include an articulated touchscreen, particularly if it could be used to adjust the autofocus point while using the viewfinder – a technique I find much quicker than pressing buttons or wiggling joysticks. A touchscreen could also have unlocked faster, more sophisticated autofocus control in live view mode, too. Articulated touchscreens seem to be associated with consumer-level cameras but not for any objective reason that I can see. Wi-Fi and GPS wouldn't have gone amiss, either, even if it had to be a removable hotshoe-mounted unit to get around the shielding of the magnesium alloy body.

Sadly, though, Canon doesn't offer bespoke camera designs to order. The 5Ds is what it is, and for the most part, it's extremely successful. If the 50-megapixel resolution appeals and you're willing to sacrifice a little performance, battery life and an extra £750, this is clearly the camera for you.