The Sony Alpha 58 is due to replace both the Alpha 57 and the Alpha 37 as the entry-level option in Sony's range of SLT cameras. And competition is tough at this price point, as this SLT will have to compete with Sony's interchangeable lens compacts and expert compacts (notably the NEX-3N and RX100). To stand out, the Alpha 58 is banking on a new 20-Megapixel Exmor APS-C sensor, an updated BIONZ processor and a viewfinder that's finally been upgraded to OLED technology.
Stylistically, the Alpha 58 is quite similar to its predecessor. Its contours and general size haven't changed much, and the camera keeps its bulky body that may be off-putting for smaller-handed users. The most noticeable change to this year's model is the screen's hinge. Instead of being hinged on the bottom, the A58 display has a more complex mount that flips out the screen from the camera body and tilts it vertically to 45°.
In practice, the new screen isn't quite as practical, however, as it loses the A57's swivel functionality. And, on closer inspection, this doesn't look to be the only step backwards Sony has taken here, as the screen resolution has been cut from 921,000 dots to 460,800 dots. This is turning into a bad habit for Sony, as the firm also downgraded screen resolution when updating the NEX-F3 with the NEX-3N. Not only is the display missing touchscreen controls, but it's also strikingly mediocre. Noise is clearly visible onscreen, even in good light conditions. And our lab tests merely confirmed the screen's crazy behaviour, with a blue overtone (peaking at 11000 K) and colour fidelity that's now even further off the mark (average Delta E = 7.3). Other downgrades in the A58 include the smoothing out of the A57's textured casing and the removal of the IR remote port (although you can still use the new RM-VPR1 wired remote).
Progress has been made in one field, however, as the viewfinder has been upgraded to OLED technology, which definitely makes viewing more comfortable! The sequential display and its rainbow effects are therefore a thing of the past. The colour temperature is a perfect 6546 K, but whites are pretty much non-existent. Colour reproduction is in line with the main camera screen, with an average Delta E of 6.3. As is often the case with this type of viewfinder, comfort of use is directly dependant on the speed of the lens you happen to be using. A zoom lens with maximum aperture at f/3.5 will hinder the experience somewhat.
As an entry-level SLR for family snapping, the Alpha 58 is intentionally easy to use. The controls and interface are in line with Sony's other cameras, with clear menus and a "?" button in the bottom right-hand corner that brings up a handy "Help" menu. This can be really useful for understanding the camera's various settings and trying out new features. It can even help you take better photos. That said, we kind of suspect that Sony's engineers keep taking the easy option here, cloning these menus camera after camera without necessarily fixing any of the incoherent or debatable features we've already spotted. The Alpha 58 is certainly easy to use, but Sony seems to be resting on its laurels.
A new processor is often a sign of speedier performances. And while the Alpha 57 was already excellent in this field, the Alpha 58 manages to take things even further, shaving around a tenth of a second off the focusing time on average in all lighting conditions. We can thank the semi-transparent mirror for that. The start-up time has been pushed down under a second and the turnaround time between two photos (which was already very fast) is only really limited by the speed of the your finger!
Note that the "Lock On AF'" function gets deactivated when you switch on the "Eye-Start AF" mode. In this mode, the camera starts the continuous autofocus automatically when you bring your eye up to the viewfinder. It works very well, even if the system can only really focus on the centre of the frame. You'll need to play around with locking the focus for off-centre subjects.
A new image processor is certainly good, but it's always more promising when accompanied with a new sensor, as is the case here. With the A58, Sony has ditched the long-serving 16-Megapixel Exmor APS-C sensor in favour of a new 20-Megapixel model—a resolution that almost looks reasonable compared with the 24 Megapixels seen in recent Nikon models (D3200 and D5200, for example). There's therefore every chance that this new sensor could see the same level of commercial success as the various versions of its predecessor.
The extra four million pixels are easily digested by the new image processing engine. Once again, the camera handles sensitivity settings well, reaching up to 1600 ISO without any noticeable problems. Pictures remain usable up to 6400 ISO, although smoothing does get stronger and shots look grainier. The A58 keeps quality under control nicely, with results that are more than satisfactory. However, contrast and saturation levels drop drastically at the highest ISO settings, while colour noise also increases (with noticeable red and magenta artefacts).
In terms of electronics, Sony's A58 is a success. However, the kit zoom lens (DT 18-55 mm f/3.5-5.6 SAM II) bridles the sensor's true potential. From full aperture to f/11, the results are flat and sharpness levels never really come into their own. At f/16 and f/22, diffraction kicks in. And it gets worse—on top of the sharpness issues (the edges of the frame actually look blurred!), contrast and saturation levels suffer despite the best efforts of Sony's heavyweight JPG processing algorithms.
This could well be down to a problem with the particular lens that we tested. Still, we have to admit that this isn't the first time we've had issues with this Sony kit lens. Quality seems to vary significantly between different versions of Sony's 18-55 mm lens (see our reviews of the NEX-6 and NEX-3N), pointing to a kind of "lens lottery" that can't go unsanctioned. After seeing quality vary over three different versions of the same lens from the same manufacturer, it's difficult to see these as isolated incidents rather than a more widespread problem. And, in the end, that's bad news for customers, who probably won't be able to keep swapping their kit lenses with Sony until they stumble upon a decent one.
The advantage of filming Full HD video rather than shooting 20-Megapixel photos is that it makes the lens sharpness issues slightly less noticeable. Here, the Alpha 58 films AVCHD video at 50 fps (interlaced), which keeps moving objects looking smooth and keeps aliasing at bay. The image is quite dark, however, making blacks very deep and affecting saturation. Movies therefore tend to look a little gloomy.
On the whole, quality is fine for shooting the odd family video. In that respect, the A58 is up there with Sony's other SLT cameras. But this particular model does have one major issue—an incessant hissing noise that's practically unbearable in quieter scenes. In fact, you can still hear it when there's some background noise. In our test lab, for example, cameras film a standard scene featuring a train set and a ticking metronome, and we could still hear the annoying hissing sound in the background of the A58's video. It sounds like you're on Blackpool sea front on a particularly windy day.