Sony DSLR-A380 Optics
Sony A380 Optics
The Sony A380 features a bayonet lens mount, which accommodates a range of Sony and Konica Minolta lenses. The Sony A380 comes bundled with a Sony 18-55mm f/3.5-5.6 SAM kit lens. A separate kit comes with both the 18-55mm and a 55-200mm f/4-5.6 telephoto zoom lens. A small button on the front of the camera releases the lens from its mount, so it can be turned and removed. The A380's CCD is smaller than a 35mm frame, so the angle of view at any given focal length will not be the same as on a 35mm camera. To find the approximate 35mm equivalent focal length, multiply the focal length of the lens by 1.5. (Thus, a 50mm lens will provide about the same view as a 75mm lens on a 35mm camera.)
The Sony A380 provides both manual and automatic focus control modes, set by the Focus Mode switch on the left side of the camera body. You can select between Auto and Manual focus modes. The Function button provides access to additional AF modes and AF Area options. The Autofocus Mode option under the Function menu offers Single-shot AF, Automatic AF and Continuous AF settings. Single-shot sets focus with each half-press of the Shutter button, while Continuous mode is constantly adjusting the focus, whether the Shutter button is pressed or not. The Automatic setting will lock focus on a still subject or continually adjust focus on a moving subject, for as long as the Shutter button is halfway pressed.
Autofocus Area also has three options available through the Function menu: Wide, Spot, and Local (manual setting). The default option is a nine-point Wide Focus area, indicated by an array of square focus areas inset within four widely-spaced brackets in the viewfinder image. (Note that only the center point utilized a cross-type sensor sensitive to detail in both the horizontal and vertical axis. The other 8 sensors are line-type, sensitive to detail in one direction only, although the four line sensors at the corners of the AF array are angled, so they'll respond to both horizontal and vertical detail.)
You can override the chosen AF mode by pressing the Spot AF / OK button in the center of the Multi-controller on the camera's rear panel, which defaults to the more accurate center AF point (the latter indicated by a target box in the center of the viewfinder). Wide AF bases its focus on the most prominent subject detail in the portion of the image that falls within the AF brackets. Spot mode bases its focus on the very center of the frame, where the square target resides. The Local setting is Sony's terminology for a manual AF area selection, and lets you manually set the main AF point by using the Multi-controller to highlight one of the nine AF points. The active AF area is briefly illuminated in the viewfinder.
Sony didn't include a depth-of-field preview button on the A380, nor on any of its new consumer models announced early 2009. Admittedly, that feature is less useful with such a small viewfinder, but this factor might put off some macro and landscape photographers.
Sony A380 AF Assist
The Sony A380 uses its built-in flash head as a very bright AF-assist light for better focusing in dim lighting. This has the advantage that the light from the flash is very bright, but the downside is that you can only get AF assist when the flash head is raised. This is a real limitation for available-light photography, as the camera can expose at light levels well below those it can focus at. (Although its low-light focusing ability is much better than average.) If the camera is fixed on a tripod, you can work around this limitation, but it's somewhat awkward: With the flash head up, half-press the shutter button to make the camera focus. Then switch the focus mode to manual focus, being careful not to touch the focus ring on the lens. Stow the flash head, and then take your picture. (But don't forget to switch back to AF mode for the rest of your shooting!)
Sony A380 Anti-Shake
The Sony A380 also employs Sony's Super SteadyShot anti-shake technology, which uses a highly sensitive accelerometer and Smooth Impact Drive Mechanism (SIDM) to move the CCD assembly itself to counteract camera movement, rather than the more common approach of moving an optical element inside the lens.
Sony claims that the Super SteadyShot anti-shake system in the A380 provides a 2.5 to 3.5-stop reduction in the blurring produced by camera shake. Translating that into real-world shutter speeds, a two-stop improvement means that a shutter speed of 1/30 second would give you the same resistance to blur from camera shake that a speed of 1/120 would without anti-shake. A 3.5-stop improvement would mean you could shoot as slow as 1/11 second and get the same results (blur-wise) as when shooting at 1/120 second unaided. Even the lower end of the specified range of effectiveness means a pretty significant improvement in one's ability to hand-hold long exposures.
When Super SteadyShot is activated, the SteadyShot scale on the right side of the viewfinder display indicates the degree of stabilization. A downside to Sony's body-based SteadyShot approach is that while you can see the results of stabilization on competing lens-based designs, you have only this scale to tell you how the A380's SteadyShot mechanism is doing. The upside, though, is that the SteadyShot scale does give you a very good idea of how hard the SteadyShot mechanism is working, so you can choose a moment when the camera is moving less to snap the shutter, thus maximizing your chances for a sharp image.
Sony A380 Anti-Dust Technology
To help combat dust particles on the CCD from changing lenses, Sony included both an anti-static coating on the CCD filter and anti-dust vibrations to automatically shake the CCD with the anti-shake mechanism each time the camera is shut off. There is also a manual cleaning mode, where the camera lifts the mirror and opens the shutter, allowing access to the sensor for use with a blower or other cleaning device. We've generally found dust-removal systems based on cameras' anti-shake systems less effective than those that use an vibrate the sensor ultrasonically, but it bears noting that no dust removal system completely eliminates the need for occasional manual sensor cleaning. Copper Hill Images is an advertiser of ours, but we'd recommend their wet/dry cleaning system even if they weren't (it's what we use in our own lab): See the Copper Hill website for details.
Sony A380 Optical Test Results
Below are the results of our optical tests on the Sony A380. We used the 18-55mm kit lens as the benchmark, since most people will buy and use the camera in this configuration.
Good performance with the 18-55mm kit lens, but some variability from sample to sample.
The Sony Alpha 380 comes with an 18-55mm kit lens, which has a typical optical zoom range of ~3x. Details were a bit soft in the center of the frame at full wide-angle, with relatively low levels of coma distortion in the corners, but some noticeable blurring and chromatic aberration in the corners of the frame. Results at full telephoto were a better, with lower corner softness and chromatic aberration, but still a hint of softness across the frame. The Sony A380 also offers up to 2x digital zoom when in Live View mode (not shown), rare among SLRs. Detail is very good because it uninterpolated and simply a 3.9-megapixel crop from the center (no loss of detail associated with digital enlargement, but it's still only a 3.9-megapixel image, vs the 14-megapixel full sensor resolution).
The particular sample of the 18-55mm kit lens used for the shots above was pretty good, so we used that lens for all our kit-lens shots with the Spring 2009 A-series models. We did find some variation between the lenses we received with the three cameras, though: It's always a good idea to check that newly-bought lenses are focusing well and evenly across the frame, but the variation we saw among the Sony 18-55mm samples we had in our lab is good reason to remind our readers of this. (Note that, other than the wide/tele/digital tele examples, other images of this subject were shot with the excellent Sony 24-70mm f/2.8 Carl Zeiss lens, to better show the capabilities of the camera itself.)
A slightly large macro area with the kit lens, with slightly soft detail. Flash throttles down pretty well.
|Macro with 18-55mm
2x Digital Zoom
The Sony A380 captured a slightly larger macro area than average with the standard 18-55mm kit lens, measuring 2.38 x 1.59 inches (61 x 40 millimeters). Detail was a touch soft at the center of the frame, and corners were very soft. (Most lenses have some softening in the corners at macro distances.) You can also enable up to 2x digital zoom which essentially crops from the center, resulting in a smaller coverage area (1.25 x 0.83 inches or 32 x 21 millimeters), but at a lower resolution (3.9 megapixels). The A380's flash throttled down for the macro area pretty well, producing only slight overexposure, although coverage was a little uneven, with the top of the frame noticeably brighter. Still, better than average macro performance for an on-board flash.
High barrel distortion at wide-angle with the 18-55mm kit lens, though hardly any distortion at telephoto.
|Barrel distortion at 18mm is 1.0 percent|
|Almost no distortion at 55mm|
The Sony A380's 18-55mm kit lens produced about 1.0 percent barrel distortion at wide-angle, which is higher than average and fairly noticeable in its images. At the telephoto end, there was only about 1 pixel of barrel distortion; for all practical purposes, none at all. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide-angle) or inward (like a pincushion -- usually at telephoto).
Moderate at wide-angle, but low at telephoto with the 18-55mm kit lens.
|Tele: Low and dull,
|Tele: Low and dull,
Chromatic aberration is moderate at the full wide-angle setting of the Sony A380's 18-55mm kit lens, showing about 7-9 pixels of bright coloration on either side of the target lines, and extending fairly far into the frame. At telephoto, chromatic aberration is much lower and hardly noticeable. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.)
Some blurring in the corners of the frame with the kit lens.
|Wide: Low to moderate softness in the
corners (upper right).
|Wide: Sharp at center.|
|Tele: Slightly soft in the
corners (upper right).
|Tele: Fairly sharp at center.|
The Sony A380's 18-55mm kit lens produced slightly soft images in the corners of the frame at full wide-angle, noticeable in a few shots. The corners on the right-hand side on this particular lens were a little softer than the left, but the softness didn't extend very far into the frame. (A different sample we saw of the same lens was softer along the right side of the frame than this one was.) At telephoto, corners weren't quite as soft as wide-angle, but the lens was slightly softer overall. There's also a bit of vignetting (corner shading) at full wide-angle, which you can see in the crops above, where the crop from the corner of the frame at wide angle is so much dimmer than the one from the center. Still, pretty good results for a kit lens, especially considering the aperture here was wide-open. (Corner sharpness and vignetting typically improve as the lens is stopped-down from maximum aperture.) Other samples we had of the 18-55mm kit lens were just average in their performance.
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Sony Alpha DSLR-A380 Photo Gallery .
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