Sony Alpha 55 at a glance:
- 16.2 million effective pixels
- 10fps continuous shooting with AF
- Built-in GPS
- Electronic viewfinder
- Full 1080i HD video
- 1,200-zone evaluative metering system
- Street price £669 (body only)
It is proving to be a big year for Sony as it has branched out from its conventional DSLR Alpha range into more alternative interchangeable-lens cameras. In May, it added the NEX-3 and NEX-5 micro-system cameras (MSCs) to the Alpha range, and just months later in August it revealed the Alpha 560, 580 and Alpha 33 and 55 models. Sony describes the latter two not as DSLRs, but as single-lens translucent (SLT) cameras.
What distinguishes the Alpha 55 and 33 SLT cameras from DSLRs is that they employ translucent mirror technology (TMT), which uses a fixed pellicle mirror rather than a moving mirror. TMT works by allowing 70% of light to pass through the mirror to the sensor, while reflecting the other 30% onto the phase-detection AF sensor. This means that the phase-detection AF system has uninterrupted exposure to light, which makes it constantly available even while the shutter is open.
This should improve the response, handling and functionality of the AF system.
By using translucent mirror technology, Sony can claim another first for its Alpha range. While a moving mirror used in DSLRs must lift with each exposure, the translucent mirror is fixed and, as a result, the shooting rate can be increased.
The Alpha 55 boasts ten frames per second while maintaining full AF, which is the fastest frame rate of any camera at this level – and for a price of just £700. Prior to the release of the Alpha 55, only the Canon EOS-1D Mark IV could claim a continuous shooting rate of 10fps with AF, while the Nikon D3S boasts 9fps.
However, these cameras cost in the region of £3,500, which is almost £3,000 more than the Alpha 55. It will be interesting to see whether the Alpha 55’s image quality can match the fast frame rate, how reliably the AF performs in this mode and how these aspects compare to the more expensive models.
Sony now boasts a comprehensive range of Alpha cameras that share many features, and it is becoming increasingly difficult to ascertain which camera is targeted at which group of photographers.
With the Alpha 55 costing just £100 more than the Alpha 33, one key point for buyers to consider is how much extra the Alpha 55 offers and whether this merits spending the extra cash. Has Sony created enough differences in the features and performance of both cameras to clearly distinguish between them and to appeal to two different levels of photographer?
Features
It goes without saying that the defining feature in the Alpha 55 is its use of translucent mirror technology. This has an effect on much of the Alpha 55’s functionality, including the viewfinder, autofocus and frame rate.
Although this technology has been used in SLRs in the past, it has proved unpopular because the light is split between the imaging plane and the viewfinder. This leaves the viewfinder significantly darker and consequently difficult to use. Sony has got round this by using an electronic viewfinder (EVF). Until now, EVFs have not been used in high-end/more advanced cameras because the technology was not up to scratch, particularly in terms of resolution.
However, while cameras such as the Panasonic Lumix DMC-G2 have shown that EVFs have improved, it is still a brave decision by Sony to include an EVF in a traditional DSLR-type camera.
The 10fps shooting rate found in the Alpha 55 is the fastest in its class, and by quite a margin – the camera’s closest rivals come in at just 7fps. Although for most users this will be ample, those extra three frames per second can really make the difference to sports and wildlife photographers. The Alpha 55’s 10fps shooting rate is available in raw and JPEG mode.
Another attention-grabbing feature of Sony’s new model is a new 15-point phase-detection AF system with three extra-sensitive cross-type sensors (also on the Alpha 33). A 1,200-zone evaluative metering mode (again found in the Alpha 33) links to the AF system and interprets the scene.
Sony was one of the last manufacturers to introduce HD video to its DSLR range, with the Alpha 55 being among the first batch launched in August. While contrast-detection AF is common for video, the phase-detection AF found in the Alpha 33 and 55 should ensure faster and more fluid focusing.
One advantage the Alpha 55 has over the Alpha 33 is a new 16.2-million-effective-pixel, APS-C CMOS sensor, which is Sony’s highest-ever resolution in an APS-C camera. The company’s sensor-based image stabilisation offers up to 4EV extra in safe handholdable shutter speeds and, combined with a maximum sensitivity of ISO 12,800 will potentially capture sharp images in extremely low light.
The fast frame rate is at the core of many handy shooting modes. Multi-frame noise reduction (NR), high dynamic range (HDR) mode and sweep panorama mode are all multiple-exposure modes; the fast frame rate means that handheld shooting is possible when using these modes, although the camera still needs to be held steady in each case. Multi-frame NR takes multiple frames and combines them for low-noise results, and in this mode ISO can be extended to 25,600. HDR mode can be found by pressing the dedicated D-Range button on the top of the camera body.
This enables a sequence of three bracketed images to be shot exposing for highlights and shadows, and producing a wider dynamic range in the final image. The sweep panorama mode is operated by panning the camera in one direction while the camera takes a series of exposures, which it then processes and combines into one panoramic image. Sweep panorama is also available in a 3D version, with an HDMI port enabling direct connection, alongside regular photos and videos, for viewing on 3D-equipped TVs.
Unlike the Alpha 33, the Alpha 55 features built-in GPS which, when activated, automatically tags photographs with data about the location. Using the supplied Image Data Lightbox software, these locations can be linked with Google maps (for more on GPS, see Features in use below). Image Data Lightbox processes image files, including raw, and adjustments can be made to key elements such as white balance, exposure and sharpness.
The Alpha 55 uses the same battery as Sony’s NEX-3, NEX-5 and Alpha 33 cameras, and gives more shots per charge than the Alpha 33 depending on whether the LCD or EVF is used during shooting and viewing.
Sony has always placed great importance on handy, fun and user-friendly features, and this is certainly the case with the Alpha 55. There are plenty of features to engage the photographer, vastly broadening his or her photographic possibilities.
Build and handling
So much about the Alpha 55 revolves around the use of translucent mirror, and this is especially true of the build and handling.
The technology allows Sony to pack all the camera’s features into an impressively compact 124.4x92x84.7mm body. The dimensions are identical to those of the Alpha 33 and, although the Alpha 55 has a similar depth to a conventional Alpha DSLR, it has significantly less height. This is achieved in part by using an EVF that does not need a prism, as optical viewfinders do.
The body sits nicely in the hand, with a rubberised front handgrip and curved thumb rest. The only difference is that the GPS capability, not found in the Alpha 33, is positioned next to the HDMI, external microphone and remote ports.
The body is made of lightweight polycarbonate and the build quality feels a little plasticky and more akin to an entry-level DSLR, but is still solid nonetheless. While the built-in flash has a rather modest output of GN 10m @ ISO 100, it can be used as a wireless trigger for Sony flashguns.
Those familiar with the Alpha range will note that the menu navigation remains the same. It is easy to move around it via the new fully articulated LCD screen (a first for the Alpha range). Operated from a hinge point at the bottom of the body, it can turn through 270° horizontally and 180° vertically.
The menu can also be navigated via the EVF and once I was able to memorise the key button layout of the body, I found I could operate it without taking my eye away from the viewfinder. The Function (Fn) button offers a host of controls, including metering and the autofocus area. Other key features such as dynamic range optimizer (DRO) and HDR mode have a dedicated button, while the panoramic sweep and 10fps modes have dedicated places on the shooting mode dial.
Shooting at 10fps is great fun, but it has some restrictions. Using a SanDisk Extreme Class 10 SDHC card, a 10fps burst in raw format lasts, at best, around 15 frames, which is 1.5sec compared to a 3.5sec burst of 35 frames when shooting Fine JPEG files.
When compared with the Canon EOS-1D Mark IV, the Alpha 55 allows a longer series of raw files to be captured, which is impressive, but a significantly shorter series of JPEG files. The EOS-1D Mark IV trumps the Sony model because it can shoot a sequence of up to 250 frames and is in a different class when it comes to JPEG image quality.
Once the Alpha 55’s buffer is full, there is a lag of around 20-25 seconds after shooting where the 10fps burst isn’t available. Having only a 1.5sec raw or 3.5sec JPEG image burst available at 10fps every 20-25 seconds is therefore not very flexible.
Noise, resolution and sensitivity
At 16.2 million pixels, the Alpha 55 makes use of Sony’s highest-ever resolution APS-C-sized sensor, combined with sensitivity of up to ISO 12,800 (expandable to 25,600 in multi-frame NR mode).
Because of issues concerning compatibility with the Sigma 105mm f/2.8 macro lens and the Alpha 55, I shot our resolution charts using the 18-55mm f/3.5-5.6 SAM kit lens set to around 50mm at f/13. Results were as I expected for a 16.2-million-pixel camera, with resolved detail at 26 and a gradual drop off to 22 at ISO 1600, and then 20 beyond that. While resolution is respectable, detail in my images is generally a little soft.
Noise levels at ISO 100 and ISO 200 are particularly well controlled. Noise starts to become apparent at ISO 800, but the results are still respectable. Even up to ISO 3200 the Alpha 55 produced reasonable results.
Chroma and luminance noise are much more noticeable at ISO 12,800, and smudging results in images that are not as sharp. However, when compared to the competition there are no specific issues worth mentioning, and I am particularly pleased with image quality in my images at ISO 100-200.
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using a Sony’s 18-55mm f/3.5-5.6 kit lens. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
Image: There is a good level of detail throughout the ISO range, and the Alpha 55 performs particularly well at ISO 100
Metering
Like the Alpha 33, the Alpha 55 uses Sony’s new 1,200-zone evaluative metering system. This is linked to the AF system, with the two technologies sharing information as to where the subject is in the frame. As this is the case, there are some scenes where spot metering is particularly useful to ensure the correct exposure for the subject.
Spot metering is only available in the centre of the frame, which I found a little restricting. When metering manually, I did so for the highlights as it is easier to recover detail in shadows than in burnt-out highlights.
My images are well exposed and the 1,200-zone system strikes a good balance between bright skies and darker foregrounds. Generally, I found the exposures to my liking and I only had to use manual exposure control in scenes with a wide dynamic range.
All the manual controls and metering modes are a fingertip away – the manual exposure control sits just above the screen so it is possible to change it without taking your eye from the viewfinder. The spot, centreweighted and multi-segment metering modes are handily accessed via the Fn button.
Autofocus
Image: Even in low light using ISO 12,800, the ten frames per second with AF shooting rate performs well
A new 15-point AF system is featured in the Alpha 55, of which three of the AF points are of the more sensitive cross type. Combined with the phase-detection AF system, this camera offers some of the fastest AF speeds I have come across in the Alpha range.
When used in Live View and video modes, phase-detection AF is particularly impressive. I photographed single-subject tracking scenes, such as my brother running on the beach or sitting on a merry-go-round, and found that the AF is responsive to lock on the subject and then maintain focus. For slightly faster-moving subjects, such as dogs, it can lag behind by a fraction of a second.
For the most part the subject was in focus in around eight out of ten frames. I also took the camera to a floodlit football training session. At times the continuous AF struggled when groups of people were moving within the frame, with an undesired subject in focus. I found that the AF system favours the subject in the centre of the frame, so placing it in this position really helped. There is a slight decrease in the number of in-focus frames when shooting in low light, but the Alpha 55 performs well nonetheless.
There is a catch to using continuous AF in the 10fps mode: it is only available in auto exposure (AE) and therefore you lose control over aperture, shutter speed, ISO and white balance. You can regain these controls by selecting single-frame AF, but in this mode the AF and exposure values from the first frame are kept throughout the sequence.
Losing the constant focusing is a disadvantage when shooting a burst of images, but if the subject is unlikely to move in and out of focus and the lighting in the scene is consistent, then single-AF offers more flexible controls for consistent results. That said, to have constant AF at 10fps is very impressive, especially considering the Alpha 55’s price.
Viewfinder, Live View, LCD and video
It is with the viewfinder, Live View, LCD and video that Sony has made some of the most significant steps forward. Instead of an optical viewfinder, the Alpha 55 features a high-resolution, 1.152-million-dot electronic viewfinder (EVF) with 100% coverage.
I was initially sceptical about this, but found that with a little practice the EVF aids handling. It is in effect a mini Live View for when conditions render the LCD screen unusable.
Like Live View, any changes made to the exposure are shown on-screen, something not possible with optical viewfinders. Menus can also be navigated via the EVF, and once I had memorised some of the basic controls on the camera body, I did not even need to take my eye away from the viewfinder to control it. The Function (Fn) button is next to the thumb position and I used the EVF frequently in combination with it, as it allowed me to control metering and autofocus. I wouldn’t be surprised if this EVF technology were to become more common in conventional style DSLRs cameras.
I particularly like the 3in, 921,000-dot articulated LCD screen. The fact that it is adjustable for portrait and landscape setup makes it is very useful for shooting at low angles or hovering over a crowd. I appreciated it when looking at autumn leaves on a tree, where I would normally have had to crane my neck. The screen is bright, with TruBlack technology giving deep blacks and extra impact. The screen is prone to fingermarks, though, and quickly becomes dirty. These marks become more apparent in bright light, so the screen needs to be cleaned regularly.
By pressing the dedicated movie record button, the Alpha 55 immediately switches from photo mode to recording up to Full 1080i HD video. Phase-detection AF helps focusing in this mode no end. It moves smoothly rather than snapping in to focus, which is visually less distracting.
The AF is audible in quiet movie scenes, but there is always manual focus if you wish to avoid audible AF noise. Further to this, and something that will please video users, is the inclusion of a 3.5mm external microphone socket. Sony has developed two microphones for use with the Alpha 33 and 55, the ECM-ALST1 and ECM-CG50, but any microphones with a 3.5mm jack are compatible.
Built-in microphones are disappointing, to say the least, so the option of an external microphone along with phase-detection AF places the Alpha 55 ahead of several of its competitors and makes the video mode the most usable in the camera’s class.
Image: The built-in digital level aids shooting even horizons
Dynamic range
By today’s standards, the Alpha 55 performs as one might expect and holds its own against competitors with a dynamic range of around 11-12EV.
In real-world settings I found the wide dynamic range produces images with fine detail, but also a good level of contrast is applied to keep images looking punchy. Using the supplied Image Data Lightbox software to process raw images, I could recover detail from dark shadow areas, but not quite so much from blown-out highlights.
For high-contrast scenes, the dynamic range optimizer (DRO+) is useful. This function can be found via the D-Range button next to the on/off switch, along with the high dynamic range (HDR) mode. DRO+ assesses the contrast of light and shadow in the subject and background, and lifts the darkest shadows for extra detail.
There are five levels of effectiveness, from weak (level one) to strong (level five). HDR mode is only available when shooting JPEGs; it captures three images including ones for highlight and shadow detail, at up to a range of 6EV in 1EV steps. If slow shutter speeds are used then a tripod is necessary, but using the quick frame rate with fast shutter speeds allows for handheld HDR shooting.
White balance and colour
Image: The piano was lit with a tungsten bulb from above. Using tungsten WB produces neutral and pleasing results, while AWB is slightly warm
Shooting in bright sunlight, overcast conditions and in both daylight and at night proved that auto white balance (AWB) is generally reliable. For the odd scene where I did not entirely like the results, the preset white balance settings can be adjusted by ±3. In tungsten light the Alpha 55’s tungsten setting produces slightly cooler results compared with AWB, although at +3 the difference is barely distinguishable. Somewhere in the middle between AWB and tungsten was as my eye saw the scene, but I leaned towards AWB, which was less clinical.
The 10fps high-speed continuous shooting mode is only available in auto exposure (AE) when using continuous AF, which can be frustrating because the exposure and AWB can change when panning the camera with the subject, and as the light in the scene changes. When this happens, the consistency of a sequence of images is compromised.
However, this is not an issue for single-frame images. To have manual control over white balance when shooting at 10fps, then single-frame AF must be selected.
Colour modes can be accessed quickly via the Fn button and, alongside the usual standard, vivid and black & white modes, there are portrait, landscape and sunset modes. Sunset mode is fun, with more saturated colours and a warm hue applied to colourful skies, but the effect may be too garish for some.
GPS
GPS is particularly useful for pinpointing the exact time and location of a photograph. This information is added to the image’s metadata, making GPS handy for news journalists and travel photographers as time and location are useful references for photo libraries.
Also, certain websites and software can automatically add extra information such as nearby historical landmarks. Latitude and longitude points can be inputted to a separate satellite navigation system to trace the exact location should a photographer want to return at a future date.
It is simple to activate the GPS in the Alpha 55’s menu screen and there is the option to automatically correct the time used by GPS on the photographs – which is handy in the case of time zone changes. However, GPS can struggle to operate in more built-up areas as high-rise buildings can interfere with the signal. On the whole, though, the GPS in the Alpha 55 is accurate.
Our verdict
Although the Alpha 55 has an unmistakably Sony Alpha exterior, what goes on inside the camera is very different. Sony has made a brave attempt to offer something new and in many respects it works.
The decision to use a fixed translucent mirror and phase-detection AF has paid off, especially when used with the unrivalled frame rate. This 10fps feature offers a good starting point for those wanting to learn how to photograph action, and some may buy the Alpha 55 just for this feature. However, it is important to note that image quality is more equivalent to an entry-level DSLR. and having to sacrifice aperture, white balance and ISO control to gain the required continuous AF is frustrating.
Phase-detection AF makes video easier to use on the Alpha 55 than on rival models. I look forward to using TMT in Sony’s higher-specified Alpha camera, which the company previewed at the photokina show in September.
In the main, there is little to choose between the Alpha 55 and 33. The former offers a higher resolution, as well as a faster frame rate of 10fps and GPS. These features merit the extra £100, especially considering the likely buyer.
Sony Alpha 55 key highlights
Dioptre
To the right of the high-resolution EVF is the dioptre correction wheel, which has ±4 adjustment
External microphone socket
Underneath a rubber cap lies a socket for an external microphone, and there are two clip-on Sony microphones available, although any can be used
Video mode
Video enthusiasts will not only appreciate the Full 1080i HD video mode, but also the fact that an external microphone can be used for improved audio quality.
SteadyShot Inside
SteadyShot Inside enables up to 4EV extra of safe handholdable shutter speeds, which can result
in sharp shooting at up to 1/8sec.
Multi-frame noise reduction
By taking a number of photos and combining them together, the Multi-frame NR mode offers
expanded sensitivity of ISO 25,600.
Digital level gauge
The three-axis digital level works by indicating whether horizons are level, but also if the camera is tilted forwards or backwards.
Function button
Plenty of key operations can be accessed directly through the Fn button, including metering, colour mode, drive mode and AF area
Movie record button
The Alpha 55 and Alpha 33 are the first in the range to feature a video mode, which can be activated directly via the movie record button
The competition
Images: Canon EOS 550D, Pentax K-r
Sony has effectively introduced a new type of camera and as a result the direct competition is not clear. In fact, only the Canon EOS-1D Mark IV can match the Alpha 55’s 10fps, and it is only in the continuous JPEG file burst where the Canon camera outshines the Sony model. However, the Mark IV is aimed at the professional-level user.
While many features put the Alpha 55 up there with higher-level cameras, its build and size align it with more entry-level or even micro-system cameras such as the Panasonic Lumix DMC-GH2. In reality, it falls somewhere between the two, such as a high entry-level, or low-end enthusiast level, model. With this in mind, the Pentax K-r, with its respectable 6fps shooting rate, and the Canon EOS 550D are currently the closest competition.
The Alpha 55 has a particularly strong video mode and features, but image quality is slightly better in the Canon model.
