Sony Alpha SLT-A55 review

6 Jan 2011

A camera with great potential, but a host of niggling irritations put paid to its chances

Price when reviewed: 
600600
4

The A55 may look like just another addition to the Alpha SLR range, but inside there are big changes afoot. Instead of using a flip-up mirror to direct light either to the optical viewfinder or the sensor, it uses a fixed, translucent mirror to split incoming light to both the CMOS sensor and a 15-point autofocus array.

The basic premise isn’t new – it’s the same principle that allows an SLR’s viewfinder and autofocus system to operate simultaneously. However, sending light to both the sensor and the autofocus has numerous repercussions. Together they make the A55 – along with its more affordable sibling, the A33 – quite unlike any other camera currently available.

Performance

Simultaneously active autofocus and imaging sensors give a big boost to continuous performance. Sony capitalises on this with a dedicated speed-priority burst mode on the mode dial, which uses fast shutter speeds to achieve 10fps shooting with autofocus – a feat previously unimaginable this side of £3,000. Exposure control is limited in this mode, but a 5.8fps continuous drive mode is available in other shooting modes.

Sony Alpha SLT-A55

The large buffer kept the 10fps speed going for 24 JPEGs or 20 RAW images in our tests. However, even when using a fast SDHC card, performance took nosedive once the buffer was full, slowing to 1.7fps for JPEGs and 0.5fps for RAW images. At ISO 1600, it slowed to just 0.8fps for JPEGs, presumably because the noise-reduction processing had to work harder. It also took around 40 seconds to flush the buffer, ready for another burst of shooting. It’s clear that the camera’s processor is the bottleneck here, rather than the memory card – it’s a shame Sony didn’t see fit to use a faster one.

The A55 differs from true SLR cameras in its use of an electronic rather than optical viewfinder. We’ve seen this before in Panasonic’s G-series cameras as well as on countless ultra-zoom models. As with the Panasonic G2, this one’s 1,440k resolution matches consumer SLRs’ optical viewfinders for detail.

Sadly, it doesn’t perform so well in practice. When Image Review is enabled to examine shots just after they’ve been taken, the screen goes blank for about a second after capture until the shot appears. That slow processor is to blame once again, and it isn’t much fun for anyone who’s used to an optical viewfinder. Image Review also makes the camera less responsive – we measured 1.3 seconds from shot to shot in the Single drive mode. Disabling Image Review reduced this to 0.5 seconds, but we never got over the frustration of having to reach for the playback button each time we wanted to review a shot.

Video

A crucial advantage of the A55’s translucent mirror is the ability to use SLR-style phase detect autofocus during video capture – a new feature for the Alpha range. Various other SLRs can record video but so far only the pricey Panasonic GH1 has delivered continuous autofocus that’s responsive enough for discerning use. The A55 is just as quick at focusing while recording video as it is when composing photos, and with its 15-point autofocus sensor, it’s very quick indeed.

Details

Price ex VAT £500
Price inc VAT £600
Overall rating 4
Performance 5
Features & Design 4
Image quality 3
Value for Money 4

Basic specifications

Camera megapixel rating 16.0mp
Camera screen size 3.0in
Camera optical zoom range 3x
Camera maximum resolution 4912 x 3264

Weight and dimensions

Weight 661g
Dimensions 124.4 x 84.7 x 92mm (WDH)

Battery

Battery type included Lithium-ion
Battery life (CIPA standard) 380 shots
Charger included? yes

Other specifications

Built-in flash? yes
Aperture range f3.5 - f5.6
Camera minimum focus distance 0.25m
Shortest focal length (35mm equivalent) 27
Longest focal length (35mm equivalent) 83
Minimum (fastest) shutter speed 1/4,000
Maximum (slowest) shutter speed 30s
Bulb exposure mode? yes
RAW recording mode? yes
Exposure compensation range +/- 2EV
ISO range 100 - 12800
Selectable white balance settings? yes
Manual/user preset white balane? yes
Progam auto mode? yes
Shutter priority mode? yes
Aperture priority mode? yes
Fully auto mode? yes
Burst frame rate 10.0fps
Exposure bracketing? yes
White-balance bracketing? yes
Memory-card type SDXC, Memory Stick Pro Duo
Viewfinder coverage 100%
LCD resolution 922k
Secondary LCD display? no
Video/TV output? yes
Body construction Plastic
Tripod mounting thread? yes
Data connector type Mini-USB

Manual, software and accessories

Full printed manual? yes
Software supplied Sony Image Data Converter SR 3.2
Accessories supplied N/A