Sony A5100 review

Sony's CSC have an enviable track record in our reviews. The old NEX brand was retired, but the cameras, unchanged in concept, continue coming under the Alpha brand. The A5100 has all the usual traits: big APS-C sensor, interchangeable lenses and a slim body that's much closer in appearance and operation to a compact camera than an SLR.

The A5100's features and price place it between the Sony A5000 and A6000 in the line-up. That means it can be seen as a replacement for the old NEX-5T (or the almost identical 5R), though it's far closer in most ways to its current-generation siblings.

The 24-megapixel sensor with 179 integrated phase-detect autofocus points comes straight from the A6000, and that bodes well for both image quality and autofocus speed. Externally, it's much closer to the A5000 than the NEX-5T. There's an integrated pop-up flash, which is much neater than the NEX-5T's clip-on unit, although it also means the A5100 can't accommodate an optional viewfinder. The side-mounted card slot is an improvement, giving easy access when the camera is tripod-mounted.

We’re disappointed that the NEX-5T’s command dial and Fn button have disappeared. As with the A5000, there are five customisable buttons on the back of the camera. However, four are assigned by default to shooting mode, drive mode, ISO speed and exposure compensation – sensible choices that we'd be inclined to leave as they are. The remaining one accesses the In-Camera Guide, which more experienced photographers won't need. However, we had a tough time choosing between the long list of options, eventually settling on AE lock. For other functions including white balance, JPEG/RAW, focusing mode, flash and metering options we had to go into the main menu, which is spread across six tabs and 23 pages. This is a big step back from the NEX-5T, which gave quick access to any six functions via its Fn button.

One advantage over the A5000 is that screen is touch-sensitive, which makes it easy to move the autofocus point. However, it took us a while to get to grips with the various autofocus-related options, which are spread out over five parameters in the menu. It's not possible to specify the autofocus area in the automatic shooting modes – only to enable a touch shutter option that focuses and shoots when the touchscreen is prodded. The touchscreen isn't used for menu navigation.

The screen is articulated, tilting up by up to 180 degrees for self-portraits. We really appreciate being able to tilt the screen by 80 or 90 degrees to shoot at elbow height. The screen's strong reflections are less appealing, making it virtually impossible to use in direct sunlight. Thankfully, setting its brightness to a Sunny Weather mode in setup menu made the image much brighter. 

The NEX-5T's performance was decidedly mixed, so it's good to find the A5100 putting in a solid performance across the board. It took half a second between shots in normal use, and 2.1 seconds with the flash at full power. Continuous mode ran at 6fps for 64 JPEGs or 23 RAW files. Thanks to the phase-detect autofocus points on its sensor, it maintained this speed when continuous autofocus was enabled – great news for tracking moving subjects, and a vast improvement on most compact system cameras (CSCs). It wasn't infallible, with roughly half of our shots in focus when tracking a running child, but that's a perfectly respectable result.

Focusing prowess at the full zoom extension was less impressive, not just in continuous mode but also when taking single frames. After extensive tests we narrowed this down to two causes. One was that the camera had a tendency to focus on foreground objects towards the edges of the frame when shooting in Automatic shooting modes. The other was that this lens isn't particularly sharp at the best of times at its 50mm focal length. We achieved better results with Sony's old 18-55mm kit lens, although the 16-50mm was sharper towards the edges of the frame. These focusing issues weren't visible at normal viewing sizes, but people who like to make large prints or to crop photos may want to invest in a better lens to make the most of the 24-megapixel resolution.

^ There's nothing wrong with the focus in this shot, taken in the middle of the zoom range. (1/250s, f/5, ISO 100, 45mm equivalent)

^ Details aren't quite as crisp in this one – although you'll need to click to view full size to notice it. (1/320s, f/5.6, ISO 100, 75mm equivalent)

Otherwise, photo quality was hard to fault, with sharp details, flattering colours and exceptionally low noise levels, second only to the Fujifilm X-M1 http://www.expertreviews.co.uk/digital-cameras/1302100/fujifilm-x-m1 (see Reviews, Shopper 311) at this price. Automatic exposure settings were generally well chosen, although the camera's occasional habit of choosing a fast 1/160s shutter speed in low light pushed up the ISO speed – and noise – unnecessarily.

^ Print-quality JPEGs at ISO 3200 are a rare treat, especially for such as small camera. (1/100s, f/5, ISO 3200, 49mm equivalent)

^ However, ISO performance is only half the story… cameras with brighter lenses beat the A5100 (with its kit lens) in low light because they can get away with using slower ISO speeds (L-R: Sony A5100, Panasonic LX100, Fujifilm X30. All set to 1/250s shutter speed)

Video quality was excellent, thanks in no small part to the full sensor readout that combines pixels from the 24-megapixel sensor rather than just discarding the pixels it doesn't need. This improves the fidelity of details, reduces moiré and pushes noise levels down. The XAVC S codec running at 50Mbit/s helps too, although it's only available when recording to SDXC cards. The A5100 can even simultaneously record 50Mbit/s XAVC S and 3Mbit/s 720p MP4 files – the latter is more useful for transferring to a smartphone and sharing online. With full access to exposure controls for video, touchscreen-controlled autofocus and a remote monitor function in the accompanying Android and iOS apps, this is just as much a video as a stills camera.

Sony A5100 Conclusion - Market forces

Mid-price cameras are often simply a blend of features from other models, possessing no technical innovation of their own. That's certainly the case here but we're not convinced that Sony has struck the best balance. We found the A5000's controls a little frustrating, but the same controls are more concerning here. While they won't hinder people who just want point-and-shoot operation, a £549 camera should really have a wider appeal than that.

Meanwhile, we're not convinced that point-and-shoot photographers are going to appreciate being able to track moving subjects in continuous mode. It's quite an advanced technique, and the menu-based controls don't exactly help people discover these autofocus capabilities.

The Sony A5000 is currently available for £270. At that price we'd happily forego the A5100's touchscreen, faster performance and more capable video capture. The Samsung NX3000 is even more tempting at just £250. For those with more money to spend, The Sony A6000 and Panasonic GX7 are available for £600 and are significantly better equipped with their high-resolution viewfinders and plentiful physical controls.

The A5100 will no doubt come down from its £549 launch price, but even so we're not sure who will appreciate its particular mix of features. We'd prefer to go for a cheaper camera and spend the difference on a prime lens.