Sony SLT A58 Review: Sony Alpha SLT-A58 with 20-megapixel sensor newly introduced

A new sensor and an advanced image processor are the ingredients for Sony’s new entry-level model. In addition to a 20.1 megapixel resolution, extensive automatic and image processing functions are possible. From automatic focusing on subjects targeted at once, to HDR shooting and panning panoramas, the Sony SLT-A58 offers virtually everything to make photography easier for the novice or intermediate SLT photographer.

Successor of this camera is the Sony SLT A68.

Brief assessment

Pros

• Image stabilizer in housing
• Quite compact and handy
• Simple operation
• A lot of potential for good image quality with the right lens

Cons

• Display partly very dependent on viewing angle
• Hardly any post-processing possibilities in the camera
• Plastic housing bayonet
• Moderate optical and mechanical quality of the kit lens

While the battle between the classic SLR cameras and the mirrorless system cameras has not yet been decided, Sony is successfully placing both technologies on the market. With SLR cameras, however, Sony relies on a fixed, partially transparent mirror and an electronically generated viewfinder image. This combination enables fast phase-comparison autofocus even in video mode and, according to Sony, should also keep the shutter release delay low, because the mirror doesn’t have to fold away first. Now, the A58 is not the successor of the A57, but a new entry-level model as a replacement for the A37, which comes very close to the A57 and is even partly superior to it.

The “Alpha” seems to be slowly running out at Sony. The Greek letter used to be the distinguishing feature of Sony SLR models and later of SLT cameras with fixed, semi-transparent mirrors and video viewfinders. Although the new case still has an Alpha sign (now in white instead of orange as before), “Alpha” doesn’t appear once in the current press release, but Sony now simply refers to the “SLT camera A58”. In April 2013, it will replace not only the SLT-A57, which was introduced a year ago, but also its smaller sister model SLT-A37, which was introduced last summer. Because the new SLT-A58 is not only more powerful, but also significantly cheaper. While the SLT-A57 is currently still around 750 EUR with standard kit lens or 950 EUR as a double zoom kit, the new SLT-A57 will be offered at 200 EUR less. As kit SLT-A58K (with the standard zoom lens SAL-1855) it will be launched in April for about 550 EUR and for 750 EUR as double zoom kit SLT-58Y with SAL-1855 (18 – 55 mm focal length) and the telephoto zoom SAL-55200 (55 – 200 mm focal length) and is thus on the same price level as the cheap SLT-37 so far. It is apparently not planned to offer the case separately.

New features on the Sony SLT-A58 include a new sensor and an improved BIONZ image processor that offers faster telephoto zoom continuous shooting and more sophisticated image processing capabilities. The new Exmor HD CMOS image sensor in ASP-C format now captures 20.1 megapixels (instead of 16.1 megapixels in previous models) with an adjustable sensitivity from ISO 100 to 16,000 (as before). The Sony-typical camera-internal SteadyShot image stabilisation (movable sensor compensates for camera shake) is of course back on board and works with all lenses. The further developed image processor is not only intended to ensure that the noise behaviour remains at least at the level achieved so far despite higher resolution, it also optimises the 15-point phase detection autofocus by means of a so-called “lock-on” mode. If the subject is captured in this mode, it will remain in focus even when moving quickly. And in telephoto zoom mode, the SLT-A58 delivers a remarkable 8 frames per second, ideal for fast sports or wildlife shots. The SLT-A58 is the first SLT camera to feature Sony’s new Triluminos technology, which is designed to deliver an expanded colour gamut, more colour shading for more vivid and realistic photos and Full HD video.

Further innovations in the SLT-A58 include a high-resolution OLED viewfinder with 100% image coverage. If desired, the viewfinder displays the effects of each camera setting on the image result in real time. A different aperture or exposure time, changes in the ISO number or white balance, but also the results of an image effect are thus already visible in the preview before the shutter release button is pressed.

Many other refinements make photography easier for beginners and advanced photographers: A function called “Auto Object Frame Function” replaces the “Auto Portrait Framing Function” known from earlier models. Not only for portraits, but also for other motifs, the camera automatically selects the image section and Sony calls this “professional image composition”. But the complete original image is saved additionally, so that one always has a backup if one is not satisfied with the automatically selected image cutout. For a striking image change, iImage Effects with eleven modes and 15 effects are available. Particularly dynamic shots are achieved with the HDR function, while a Sweep Panorama function automates super-wide landscape shots.

Ergonomics and Workmanship

The Sony SLT-A58 is very similar to its big sister, the A57. A little bit more massive than its predecessor, it is still as handy as a big bridge camera. The plastic case also fits well in the big hand, although the little finger only finds room under the well rubberized handle. The index finger reaches the main switch located around the shutter release button just as conveniently as the wheel, with which aperture, time, program shift and, after pressing the corresponding button, other exposure parameters can be set. And the thumb finds its place on the back without accidentally pressing switches. Nevertheless, the cross rocker and other buttons can be reached without dislocation. The video trigger is also very cleverly positioned close to the eyepiece, so that inadvertent triggering is hardly possible.

The flaps for the battery and memory cards look sufficiently solid and the rubber covers of the connectors serve their purpose. Despite the quite good workmanship, the case looks a bit cheap, which might be due to the used plastic and the surface finish. But maybe also on the bayonet, which unfortunately is also made of plastic on the camera side and offers a view into the mechanical interior with quite large slits. In dusty or humid environments this could become a problem. The bayonet of the kit lens is also made of plastic and has to be pressed against the spring pressure of the locking pin and AF driver when connecting it to the camera, which takes some getting used to at least. After all, it glides smoothly and accurately to the stop. Really cruel is the included camera strap, because it is hard and scratchy and it cuts unpleasantly into the neck. Better would be to use another camera strap.

The switches and wheels convince again with an exact pressure point and a clean detent, only the second stage of the release could be a bit smoother. The tripod thread is exemplary made of steel, is located exactly in the optical axis and allows access to the battery even with the tripod plate mounted.

The operating mode selector on the upper left side of the housing provides twelve basic functions. It can be turned in both directions without limitation, so that every position can be reached by the shortest route. The selected settings can be influenced with the Fn key. Basically, it is not necessary to go to the menu, as all essential recording parameters can be adjusted in this quick menu. But also the main menu is clearly arranged in sensible function groups, each of which contains only one screen page.

With a diagonal of a good 6.9 centimeters (2.7 inches), the display, which is somewhat below average, has a sufficiently fine resolution of around 460,000 pixels and shows a brilliant picture. It can be folded downwards by about 50 degrees, and upwards the joint extends into the horizontal plane. When viewed from the side, the brilliance and sharpness decrease only slightly, but when viewed from below, the image even tilts into the negative. This can be particularly annoying if the camera is held above your head and you want to take pictures downwards.

The electronic viewfinder, which is automatically activated when the eye approaches, is particularly appealing. It comes very close to an optical viewfinder, you get used to occasional jerking and the slightly lower brightness very quickly. In the dark, however, the electronic viewfinder shows its advantage. As with a residual light amplifier, the subject can be observed brightly and clearly. The fact that hissing and jerking increases can be overcome. Different grids and all recording parameters up to the histogram can be displayed independently on the display and in the viewfinder. On the upper side there would still be some space for a few more switches, which Sony unfortunately didn’t use. On the other hand, the A58 appears tidy and remains clearer for the intended target group.

Equipment

The SLT-A58 is a camera for beginners as well as for advanced and ambitious photographers. The “superior automatic”, marked with a golden symbol, not only decides which program best suits the subject, but also whether high contrasts can be mastered with a fast series of images. But not only this method called Auto-HDR uses the fast frame rate of the A58, it also reduces image noise and camera shake. Those who feel more in control can set one of the other full, scene, program or semi-automatic modes and for control freaks there is the manual mode. The camera grows with the demands, so to speak. The flash pops up automatically when needed, but can also wait for the photographer to press a button if desired. Of course, one should not expect miracles from this little light giver. At least it illuminates the kit zoom at the short end quite decently and leaves only a narrow lens shadow at the lower edge of the image. Long-term synchronization and flashes to the second curtain are possible as well as remote control of a system flash. If the light is not enough for you, simply slide an external flashlight into the standard accessory shoe. Sony has now abandoned the annoying quirk with its own flash connection even in the smallest model. Sony includes an adapter so that older system flash units can also be connected. This is the way it has to be and not the other way around.

In video mode, the A58 could adjust the sharpness quickly and without pumping due to the semi-transparent mirror, but unfortunately it doesn’t do so with the kit lens. Instead, the sharpness is adjusted in thrusts, which is accompanied by clear engine noises. The zoom ring is quite smooth-running, but produces a scraping noise, which also lands on the audio track. The Carl Zeiss 1.4/50mm, which was also available to us for the test, shows that this is much better. The 1,500 euro lens does its job evenly and almost silently and keeps the subject in focus. Of course, the comparison is already limping due to the immense price difference, but we would have expected a bit more quality for the kit lens from Sony. A small consolation may be that you can connect an external microphone via a 3.5 mm jack plug to block out hand, zoom and AF noise. This is not a matter of course for a camera in this price range. Otherwise, the Sony offers full HD resolution with 25 full frames per second. The whole thing can be saved in AVCHD mode at different bit rates.

By the way, the autofocus works quite fast and accurate without setting records. A quarter of a second at the short end and a third of a second at the long end elapse until the shot is fired; pre-focused, the delay is in the hundredths range. Sony provides two aids for manual focus. On the one hand, edges that are recognized as sharp can be highlighted in color, and on the other, a focus magnifier can be placed on the dipper button. It’s a pity that the kit lens has to be switched between AF and MF with a slider, so manual readjustment of the autofocus is impossible. The narrow lens mount acts as a sharpening ring, requiring only a slightly sensitive quarter turn from near to far, and is therefore more of a stopgap.

The autofocus with its 15 fields is designed for face detection and tracking, but the A58 also tries to keep any previously marked subject in focus. Sony also uses this Scene Recognition feature for the automatic picture frame, where the photo is cropped around the main subject and the cropped area is interpolated to full image size. Fortunately, the image result is saved in addition to the original, so that nothing can be lost unintentionally.

The highest continuous shooting rate is only achieved by the smallest SLT with a trick: In the “Tele zoom continuous shooting” setting, an approximately 5 megapixel image section from the center of the sensor is recorded at 8 frames per second. Because of the image detail, the focal length seems to increase by a factor of two. The Sony also captures panning panoramas, both horizontal and vertical, with a fast frame rate. With a little practice this works quite well, only with moving subjects double contours are created and by panning also slight motion blur. At full resolution, the A58 manages about 5 frames per second, which it holds out for about 8 frames, after which the speed slows down.

Very pleasing is the image stabilizer integrated into the camera body, but it does its work very much in secret when taking pictures. Only at the moment of exposure does it unblur the image; the viewfinder image is not stabilized. After all, the stabilizer works with any lens.

With the SLT-A58, the image-editing grouch will acquire eleven more or less usable creative modes, including the popular miniature effect, various black and white conversions and much more. They cannot be subsequently applied to existing photos. In general, the subsequent editing options are limited to the minimum, rotate and delete, that’s it.

Image quality

Sony adds four megapixels to the SLT-A58 in comparison to its predecessors, which even puts the actually “bigger” A57 in the shade.

To get right up front: The higher resolution does not harm the parameters that are sensitive to it. Noise, grain size, input dynamics and signal-to-noise ratio are equal to or even better than the much praised A57. Color noise is virtually meaningless, only at the highest ISO values does it scratch the interference limit. Up to ISO 1,600, all other parameters mentioned above are inconspicuously held back and rise only gently above that. The input dynamic range remains at over 10 f-stops throughout, only above ISO 6.400 does it drop below 9, so the 20 megapixels are not disturbing. It looks different when you look at the resolving power of the lens. Practically no increase can be detected compared to the models with a lower number of pixels; the measurement curves remain at a measly 35 line pairs per millimeter (Lp/mm), and this only in the center of the image at the short end and open aperture. The kit zoom has the best image quality at medium focal length and f-stop 5.6 to 11, but even there the 40 mm bar is clearly missed. If the subject is in the center of the picture, the DT 18-55 mm can be used with open aperture, but you shouldn’t expect crisp sharpness. This is surely also due to the only moderate re-sharpening of the camera, which is to be rated as positive, as there are no sharpening errors worth mentioning. Here the photographer can subsequently lend a hand.

Darkening of the edges is hardly an issue, but distortion in wide angle is. Three percent barrel-shaped are visible to the naked eye and also disturbing in architectural photos. The tonal value transfer is prepared rather crisply for direct printing, so that corrections in image processing are not necessary at this point. The Sony doesn’t take colour fidelity quite so seriously, but it does tend to have a bit more saturation in the warm colours, which is generally perceived as pleasant. The white balance, on the other hand, is very accurate and gives no cause for criticism.

Conclusion

Sony has launched the SLT-A58, a camera that appeals to both beginner and advanced photographers. Packed with electronic helpers and automatisms that hardly allow any technically spoiled images, it also allows full manual control. The fast autofocus could even inspire the videographer, if it weren’t for the very modest kit lens. It’s a pity that Sony is giving away a lot of potential, which is definitely in the A58, here. Only when equipped with a usable lens does the new one show what it is really made of. A few other small weaknesses, like the cheap appearance or the questionable plastic bayonet, may be overlooked in view of the fair price.

Sony Alpha 58 (SLT-A58) Datasheet