Sony Alpha SLT-A55

Pellicle, or translucent mirrors, are not new to cameras. Such an implementation was already found in film-based SLRs since 1965, but it was only this year that it made its way into dSLRs. The Sony Alpha SLT-A55 is the first dSLR to employ such technology, and by doing so, the camera gains a fast 10fps burst shooting speed and continuous phase-detection autofocus in video-recording mode. However, the A55 has more tricks up its sleeve than those just mentioned. It is probably also the first in its class to have an onboard GPS module for geotagging, as well as first to employ a high-resolution electronic viewfinder instead of the optical variation typically found in other dSLRs.

Design

The A55's body is constructed from polycarbonate plastic, which helps reduce the weight of the camera. At 440g (without lens), it's one of the lightest dSLRs on the market you can find now, though this will depend on what lens you attach to the snapper.


The front of the Sony camera looks like other dSLRs. The shutter button above the command dial is positioned at a slant to facilitate operation. As with most entry-level dSLRs, the handgrip feels a tad too small, but the compact form factor is an attractive preposition for users looking for a petite dSLR.


On the top left end of the A55, you'll find the mode dial, which turns 360 degrees. On the other end are keys for toggling between the EVF and LCD, as well as a control for the D-Range Optimizer. There are more buttons located at an angle toward the user, namely Menu, exposure compensation, exposure lock and a dedicated movie-recording control. Again, this design is meant to make these buttons more easily accessible to users and we found we were able to quickly get to them with our right thumb.

There is also a pair of microphone located behind the popup flash for stereo audio recording.


Around back is a swivel LCD, which can be folded flat against the back of the camera. This is useful as you can flip the screen inward during transportation, reducing the risk of scratching the panel. To the right are a four-way navigation pad, which can be pressed to access display information; self-timer/burst mode; ISO setting; white balance; and autofocus setting. There's also a Fn (function) button to call up a more extensive shooting menu, as well as playback and delete keys.


At the side of the A55 are ports for mini-HDMI, USB and remote control ports and 3.5mm microphone output. Beside the lens mount is a switch for autofocus or manual focus.


The bottom of the dSLR houses the battery compartment and SD/SDHC/Memory Stick PRO Duo slot.

Using the A55 wasn't much of a problem for us since we are accustomed to using Sony dSLRs. Once you are familiar with the button positions, you can probably access them without having to take your eyes off the viewfinder. It should also be noted that due to the swivel screen implementation, the A55 cannot be fitted with a battery grip at the bottom of the camera.

Features

The key highlight of the A55 is the translucent mirror, which, unlike a typical dSLR, doesn't flip up when taking a shot. Instead, it allows a portion of light to filter through while reflecting the remainder up to a phase-detection autofocus sensor and the EVF. Phase-detection AF is employed in dSLRs and is faster than contrast-based AF, which is what dSLRs use when in Live View or video-recording mode. So, for the Alpha, it is able to continuously track a moving subject via phase-detection AF no matter what shooting or recording mode you are in, and that's a big deal. This is because most video-enabled dSLRs on the market now do not offer AF while filming, or the AF is just too slow and inaccurate.

We will inspect the AF performance in a later section.

The Sony Alpha is neither an entry-level nor a midrange dSLR. Instead, it sits somewhere between these two categories. Sony told us the camera is geared toward advanced amateurs, and we think its closest competitors are probably the Canon EOS 550D and Nikon D5000. Here's a comparison chart between the trio's specifications.

Specifications/model	Sony Alpha SLT-A55	Nikon D5000	Canon EOS 550D
Sensor resolution	16.2 megapixels	12 megapixels	18 megapixels
Dimension/weight	124.4 x 92 x 66mm/440g	127 x 104 x 80mm/560g	128.8 x 97.3 x 62mm/530g
LCD size	3-inch swivel	2.7-inch swivel	3-inch fixed
Viewfinder	1.44-megapixel EVF	Optical	Optical
Max. video resolution	1,920 x 1,080 pixels	1,280 x 720 pixels	1,920 x 1,080 pixels
Audio	Stereo	Mono	Mono
Burst mode	10fps	4fps	3.5fps
ISO range	ISO 100 to 6,400 (expandable to 12,800)	ISO 100 to 6,400	ISO 100 to 6,400 (expandable to 12,800)
Image stabilizer	Sensor-shift (in-body)	Optical (via lens)	Optical (via lens)
Memory media	SD/SDHC/SDXC and Memory Stick PRO Duo	SD/SDHC/	SD/SDHC/SDXC
Related links		Review	Review

As with most other GPS modules, the geotagging feature of the A55 is best used outdoors under a clear sky with few tall buildings in the vicinity. While this was easy enough when we were in the suburbs, in Singapore's city center, where tall buildings can be found at almost every corner, we had some difficulty getting the GPS to lock onto our position. It required a couple of tries in different spots before we managed to obtain a good signal from the satellite.

The A55's EVF has a resolution of 1.44 megapixels, which provides a fine view of the scene. The specifications are on par with the Olympus VF-2 EVF that complements the company's line of Pen Micro Four Thirds cameras. The Sony EVF's refresh rate is fast and, if you shoot under daylight conditions, the performance is probably not discernible from an OVF. One advantage the EVF has over the optical variation is that in low-light environments, the camera would digitally boost the scene so we would be able to get a better view. That said, using an OVF consumes less power and this translates to more shots for the Sony So, it's a compromise users will have to make if they choose the A55.

Sony first debuted the 3D Sweep Panorama feature in its NEX and recent Cyber-shot shooters. Now, the company has ported the same feature over to the Alpha line. The A55 is able to capture a panoramic view by panning it across the scene. Take note that you have to maintain a consistent speed when moving the dSLR for the best effect. It takes practice, but the results are worth it.

There is also a level tool (which looks like the display in a fighter jet), which tells you if the snapper is on the same plane as the horizon. This feature will appeal to landscape and architectural photographers who want their shots to be leveled at a certain angle.

The video mode for the A55 is pretty limited. You have a choice of recording in AVCHD or MP4. In the former mode, there's only 1,920 x 1,080 resolution. For MP4, you have a choice of 1,440 x 800 pixels or VGA (640 x 480 pixels). Users should also note that there is no manual mode while filming, and you cannot change the frame rate.

Performance

We tested Sony's claim for the A55's (with the 18-55mm kit lens) 10fps burst shooting and found it to work flawlessly. Most importantly, the continuous autofocus tracking was quick to react to our moving subject as well. Although it didn't manage to get all the frames in focus, we had eight good shots out of 10, and that is extremely commendable for a dSLR in the advanced amateur category. The same goes for video recording. We were able to shoot a clip of a remote-controlled toy car zipping around and the camera worked to keep the vehicle in focus.

Startup took about half a second, while shutter lag with prefocus was almost negligible. Without prefocusing, though, the camera's shutter lag measured approximately 0.3 second.

We were curious to see if leaving the GPS option activated would dent the battery performance of the Alpha significantly, so we left this on for a whole day while shooting. Understandably, the geotagging feature would require some juice to remain active, but it didn't impact the battery much. We were able to get about 250 pictures and a few minutes of full-HD videos with the GPS turned on. That said, the battery life depends on your usage pattern. Bear in mind also that we set the camera to Power-saving option to put it on standby mode after 1 minute of inactivity.

Image Quality

The A55 has an ISO range of 100 to 12,800, which is typical of most current dSLRs. From our comparison chart below, we noticed the Alpha performed quite well. Pictures taken at ISO 100 to ISO 800 looked clean and free of noise, while ISO 1,600 images appeared very usable, too. Digital artifacts crept into the photos only when we bumped the ISO sensitivity up to 3,200. There were some discolorations in the pictures we snapped at ISO 6,400, so that's probably the limit of this Sony.



Colors generated by the A55 (at default setting) looked natural and nicely saturated, though we noticed the camera tended to underexpose the scene slightly, resulting in a darker image. To overcome this, we used the exposure compensation function and dialed it up by 0.3 stop.

You can see more pictures snapped by the A55 here, and the video sample embedded below.

Conclusion

The Sony Alpha SLT-A55 is in some ways a revolutionary dSLR. This is because for its affordable price of S$1,249, it packs features such as 10fps burst mode and continuous AF (when shooting and filming) in the hands of the average consumer. Also, the implementation of the translucent mirror is a good one, proving that fast-performing dSLRs aren't only meant only for professionals. Compared with its rivals, the A55 offers the most bang for the buck. But first, Sony will have to educate consumers on the advantages of the A55, something most people weren't not aware of when we showed them the camera.

Image Samples (taken with the 18-55mm F3.5-5.6 kit lens)

ISO set at Auto, with value of ISO 160, shutter speed of 1/40 and at F4. Other shooting settings such as D-Range Optimizer were at default. (Credit: Leonard Goh/CNET Asia)


ISO set at 1,600, shutter speed of 1/40 and at F5.6. Other shooting settings such as D-Range Optimizer were at default. (Credit: Leonard Goh/CNET Asia)


ISO set at 1,600, shutter speed of 1/30 and at F8. Other shooting settings such as D-Range Optimizer were at default. (Credit: Leonard Goh/CNET Asia)


ISO set at 400, shutter speed of 1/80 and at F5.6. Other shooting settings such as D-Range Optimizer were at default. (Credit: Leonard Goh/CNET Asia)