Sony Alpha SLT-A99 In-Depth Review
Current Sony users will find the A99's automated and image enhancement features quite familiar. Sony sees no need to prune seemingly entry-level features like effects filters or smile detection from its flagship model. We'll take this opportunity, however, to re-examine a few of the features with more obvious appeal to experienced DSLR shooters.
Sweep Panorama has been a Sony mainstay for a while now and has been much copied by other manufacturers. The Sony implementation remains the best we've seen. Simply press the shutter button and pan the camera. The software does a great job of stitching the images together, regardless of how stable you are during the pan. Of course, using a tripod - as we've done in the samples below - will give the best possible results. Because the camera is shooting a sequence of images, however, any object moving across your scene risks appearing multiple times or being stretched or compressed, depending how it's moving relative to your sweep. On average though, stitching errors, when they occur are rarely noticeable except at higher image magnifications.
|Standard sweep panorama, captured panning to the left|
The panorama system is relatively flexible. Not only can you specify the direction of the pan, the importance of which we'll discuss in a moment, there are two widths of panorama available and you can shoot vertically, as well as horizontally - effectively opening up a further two options if you sweep with the camera in portrait orientation, though it'd be nice not to have to delve into the main menu to adjust these settings.
|Standard sweep panorama, captured panning to the right|
The camera locks metering during the panorama, which is entirely sensible. When shooting scenes that span varying brightness levels though, be aware that the camera meters from the initial frame. In the example above, the sweep began on the left side of the scene, with the camera facing into a backlit horizon and therefore choosing a darker exposure. Compare this to the more pleasingly exposed image at the top of this page. It was shot seconds earlier from the same location, but this time with the camera metering from the right edge of the scene. Given these results, in high contrast situations we recommend beginning your pan from the darker portion of the actual scene to ensure an adequately bright exposure.
|12416 x 1856 'Wide' sweep panorama, captured panning to the left|
In the examples above you can see Sony's wide panorama setting which yields a 12416 x 1856 pixel image, followed by a 100% crop from the scene. The level of detail here is very good, in line with what we've seen from previous SLT models. With the camera amounted on a tripod, as we've done here, you can produce results that suffer little if any, in comparison to a single shot image. When printed at a high resolution of 300ppi, the full image would yield a 41-inch wide print.
Clear Image Zoom
In situations where you'd like to have more reach than your lens is capable of, the A99 offers three digital alternatives. One of them is the 'smart teleconverter' option. This is not a magnification feature, rather the image is cropped at one of two possible crop factors so that the central portion of the image occupies a larger portion of the frame. The result is a sub-24MP image file, akin to what you would achieve with a constrained crop tool in Photoshop.
A second option is the Clear Image Zoom feature that was introduced with the SLT-A57. With it, Sony promises improved performance over its normal digital zoom and up to a 2x magnification zoom with, 'nearly imperceptible degradation' compared to an optical zoom. As you'll see in the examples below, we find that claim overly optimistic at best. In the comparison below, we mounted the A99 on a tripod and shot the same scene with the excellent Sony 24-70mm F2.8 ZA SSM Carl Zeiss Vario-Sonnar T* lens at a 35mm focal length with both Clear Image Zoom and normal digital zoom enabled. We then shot the scene with the lens set to 70mm with no zoom enabled.
|1/125 sec. @ f/6.3: Lens at 70mm with no additional zoom enabled.|
|Lens at 70mm, no additional zoom (100%)||Lens at 35mm, 2x Clear Image Zoom (100%)|
As you can see, there is clearly a penalty to be paid in image quality and detail for the use of Clear Image Zoom compared to an equivalent magnification by way of optical zoom. While this should come as no great surprise, it's disappointing just how little benefit Clear Image Zoom seems to offer over even the 'traditional' digital zoom that predated it. In the examples below we compare a 2x zoom using both Clear Image and standard zoom options and are hard pressed to find significant difference between them.
|Lens at 35mm, 2x Clear Image Zoom (100%)||Lens at 35mm, 2x std digital zoom (100%)|
Given these results, we fail to see much benefit, other than convenience, of an in-camera digital zoom versus performing the upsampling task in Photoshop. The latter option not only gives you the option to fine-tune results to minimize stair-stepping and edge halos, but also preserves the outer portions of the image that were lost during magnification, should you later wish for a slightly different composition.
Sony provides two methods for dealing with high contrast scenes. We've discussed the single-shot Dynamic Range Optimizer (DRO) option most recently in our Cyber-shot RX100 review. The A99 also features Sony's very effective multi-shot HDR mode, which uses three different exposures to maximise the range of brightness information it can capture, then blends the exposures into a single image. This is a JPEG-only mode and unlike the RX100's implementation you do not have the option to save the middle of the three exposures as a separate file alongside the composite image. The Auto setting does a good job of setting an appropriate exposure bracketing based on scene analysis (as you can see below), but you can also manually instruct the camera to cover a three-shot bracketing range of between 1 and 6 stops EV.
|HDR Off||HDR Auto|
In the example above, enabling HDR mode at its auto-bracketing setting provides highlight and shadow information that could not be captured in a single exposure. This results in a fairly natural looking tonal distribution that avoids an overly processed HDR look (note that we added the histogram to these preview images to show this more clearly - click the images above for the untouched original files).
Of course, users who desire the utmost flexibility can do this manually by bracketing and then blending separate exposures in Photoshop, but the quality of Sony's alignment and blending algorithms make in-camera HDR a viable and extremely convenient option.
|HDR Off 100% crop||HDR On 100% crop|
|HDR Off 100% crop||HDR On 100% crop|
In these 100% crops you can see that enabling HDR captures color-accurate highlight data that was clipped in the single image exposure. With a well-calibrated monitor you can see that shadow detail is opened up a bit as well, but the differences here are much more subtle in comparison to the highlight recovery.
Multi-shot noise reduction
Another feature now standard on Sony's SLT and mirrorless interchangeable lens cameras is multi-shot noise reduction - which combines six images taken in fast sucession into a single, cleaner shot. Why does this count as 'noise reduction?' Because noise occurs randomly, so combining multiple shots allows the camera to average that noise out. The system is clever enough to use information from the image stabilization system so that it only uses information from relatively unshaken images, taken of the same subject.
The results are pretty impressive. As you might expect, in the low-light circumstances in which you might want to use it, the slight shake between images means that really fine detail isn't perfectly sharp around the edges. However, it is undeniably less noisy than the conventional, single-shot version.
|ISO 6400||Multi-Shot NR ISO 6400|
|100% Crop||100% Crop|
The multi-shot noise reduction system underpins the 'Hand Held Twilight' mode, which is available either from the SCN position on the mode dial or automatically, if the camera thinks it's needed, in Superior Auto mode. In both instances, it will use as many of the shots as it can, but will ignore shots with excessive movement (either camera shake or subject movement) in them, so that your final image isn't a confused mess.
The SLT-A99V (the variant sold in most territories) features built-in GPS, which can append location information into the exif data of still and movie files. This data can be read by an increasing number of software platforms and photo-sharing websites, including Sony's Picture Motion Browser, which is bundled with the camera. In our experience of using the A99's GPS, we've found that it works very well. The first time the camera achieves a satellite 'lock' can take around 3-4 minutes but after that, if you head indoors or power the camera down then turn it on again, it picks up a signal within a few seconds.
|This icon in the camera's status display designates that GPS is switched on, and the camera is receiving geolocation information.
This display screen is taken from the Sony A77, but the GPS icon and its placement are identical on the A99.
|GPS is turned on in the A99's custom menus. From here you can also activate automatic time correction, which lets the camera maintain accurate time/date information using GPS. To speed up GPS data acquisition you can download 'GPS Assist Data' via Picture Motion Browser and upload it to the camera via direct USB connection or from a memory card.|
|When GPS is turned on, geolocation data is appended into the metadata of still and video files. Here's how the data is displayed in Adobe Bridge CS5.|
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