Sony DSLR-A550 Exposure

Saturation & Hue Accuracy
Very good overall accuracy and saturation, with relatively minor shifts in hue and intensity.

Saturation. The Sony A550 pushes strong reds, orange, dark blue and some greens, browns and purples just a little, but actually undersaturates aqua and cyan tones slightly. Its overall color saturation (11.8% oversaturated) is a bit higher than the A380, but quite typical for a consumer oriented SLR. Most consumer digital cameras produce color that's more highly saturated (more intense) than found in the original subjects. This is simply because most people like their color a bit brighter than life.

Skin tones. Here, with the color balanced properly for the light source, the Alpha A550's skin tones looked just about right. There were some slightly reddish tints in places, but overall skin tones looked natural. Where oversaturation is most problematic is on Caucasian skin tones, as it's very easy for these "memory colors" to be seen as too bright, too pink, too yellow, etc.

Hue. The Alpha 550 showed only a few small color shifts relative to the mathematically precise translation of colors in its subjects, but had pretty good accuracy overall. Most noticeable were shifts in reds toward orange, orange toward yellow, cyan toward blue, as well as some shifts in yellow and purples. (The cyan to blue shift is very common among the digital cameras we test; we think it's a deliberate choice by camera engineers to produce better-looking sky colors.) Hue is "what color" the color is.

Saturation Adjustment
The Sony A550 has a total of seven saturation settings available, three above and three below the default saturation. This covers a pretty wide range of saturation levels, about as wide a range as you're likely to find photographically relevant, apart from special effects that are arguably better achieved in software. The fine steps between settings mean you can program the camera to just the level of saturation you prefer, a feature we look for in cameras.

The table above shows results with several saturation settings including the default and both limits. See the Thumbnails index page for more (look for the files named A550OUTBSATx.JPG). Click on any thumbnail above to see the full-sized image.

Exposure and White Balance

Indoors, incandescent lighting
Good color with Incandescent and Manual white balance settings, though warm results with Auto white balance, and cool results with 2,600 Kelvin. Slightly above average positive exposure compensation required.

Indoors, under normal incandescent lighting, the Sony Alpha 550 produced overly warm color with its Auto white balance setting. Both the Incandescent and Manual settings produced more accurate results. It was a bit of a toss-up between them, as the Manual setting was the most accurate while the Incandescent option a little warmer; We suspect most users would prefer the slight warmth of the results with the Incandescent white balance setting, as being more representative of the original lighting, without the very warm cast of the Auto setting. The 2,600 Kelvin setting, which matches the temperature of our lights numerically, resulted in a slight blue cast. At +0.7 EV, the exposure compensation required was slightly above the average for this shot. The average among cameras we've tested is +0.3 EV. Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.

Outdoors, daylight
Very good results under harsh lighting, with good handling of contrast, detail, and color.

Outdoors, the Sony Alpha 550performed well, but required slightly higher than average exposure compensation of +1.0 EV for our "sunlit" portrait shot to keep the face bright. The average among the cameras we've tested is +0.7 EV. Contrast is a little high, as you might expect under such harsh lighting, but the camera does a very good job of holding onto detail in bright highlights. Despite the apparent brightness, there are actually very few clipped highlights in the model's face and shirt, with most of the clipping occurring in the pendant and flowers. Some shadows are quite deep and plugged, though. Only a few highlights were blown in the House shot at the default exposure as well, however there are some deep shadows present as well. Color balance is good as well, with good white balance and saturation considering the bright lighting. Finally, the camera's contrast adjustment did a very nice job of toning down the exposure without creating any strong color variations in the skin (though skin tone did change slightly - See the Contrast series under the Extremes section below). Overall, very good performance.

See full set of test images with explanations
See thumbnails of all test and gallery images

Resolution
Very high resolution, 1,800 ~ 2,000 lines of strong detail.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 2,000 lines per picture height in the horizontal direction, and about 1,800 in the vertical direction. Complete extinction didn't occur until around 2,800 lines in the horizontal direction, and over 3,200 lines in the vertical. Unusually, we weren't able to do much better with Adobe Camera RAW processed RAW files, which indicates that the camera is doing a pretty good job here. Use these numbers to compare with other cameras of similar resolution, or use them to see just what higher resolution can mean in terms of potential detail.

See full set of test images with explanations
See thumbnails of all test and gallery images

Sharpness & Detail
Good detail but slightly soft images at default settings, with relatively minor edge-enhancement on high-contrast subjects. Low to moderate noise suppression visible at base ISO.

Sharpness. The Sony A550 produced very good detail, but softness in its kit lens didn't show off the camera's abilities to best advantage. The crop of the house and trees above is from an image shot with Sony's 24-70mm f/2.8 Carl Zeiss zoom, a really excellent optic, and shows the very good detail the A550 body is capable of. Though images are still slightly soft with the sharper less, and some minor edge enhancement artifacts are visible on high-contrast subjects such as the crop above left, overall results are still pretty good. (You can always adjust in-camera sharpening for sharper JPEGs, but best results would be obtained by dialing down the in-camera sharpening an using strong/tight unsharp masking in Photoshop or other image editing software, or by shooting RAW and using a good RAW converter.) Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.

Detail. The crop above right shows low to moderate noise suppression, as the darker areas of the model's hair still show a lot of detail. Individual strands do merge together when local contrast is low, and as shadows deepen. All in all, a good performance here, especially considering the high resolution. (Sony seems to have made real strides in their noise-reduction processing in the last year or so, as this round of Alphas do a much better job of holding onto subtle subject detail than did last year's models.) Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears.

RAW vs In-Camera JPEGs
As noted above, the Sony A550 produces slightly soft JPEG images at default settings. More detail can be obtained from carefully processing RAW files, without introducing additional sharpening artifacts. Take a look below, to see what we mean:

In the table above, mousing over a link at the bottom will load the corresponding crop in the area above, and clicking the link will load the full resolution image. Examples include in-camera Fine JPEG, RAW file processed through Sony's Image Data Converter SR version 3.2 software with maximum sharpening applied, and RAW file processed through Adobe Camera Raw version 5.7, then sharpened in Photoshop. For the Sony A550's images shot with sharp primes or high-end zooms, I found best results with strong but tight 300% unsharp masking with an 0.3 pixel radius. (As above, this shot of the house & trees was captured with the Sony 24-70mm f/2.8 Carl Zeiss lens, to show the camera's detail rendering when not limited by the kit lens.)

ACR renders colors somewhat differently than either the A550 or the Sony software, so the greens in the trees and blues in the sky are a bit different. However, there's no mistaking the increase in detail from the ACR converted RAW, regardless of changes in color or tone. The ACR conversion does show quite a bit more noise than the in-camera JPEG or Sony IDC conversion. You can always turn up the noise reduction in ACR, though.

ISO & Noise Performance
Better high ISO noise performance than previous Sony APS-C SLRs, with very good results up to ISO 800.

The Sony A550's images are quite clean at ISO 200, and ISO 400 is almost as good. Some noise "grain" is noticeable at ISO 800, and there's a bit of chroma noise in the shadows, but the camera doesn't smudge away as much fine detail as most others at this ISO, except in low-contrast reds (see below). There's some stronger smudging of fine detail at ISO 1,600, but the A550 still does better than most at this ISO for its resolution. At ISO 3,200, fine detail suffers from more aggressive noise reduction, but there is still some detail left, and chroma noise really isn't an issue. Detail takes larger hit at ISO 6,400, and above. There's also quite a bit of chroma noise in the form of purple and yellow blotching, especially at ISO 12,800. Overall though, these are very good results considering the size of the camera and the resolution offered. As always, see the Print Quality section below for maximum recommended print sizes at each ISO.

A note about focus for this shot: We shoot this image at f/4, usually using one of three very sharp reference lenses (70mm Sigma f/2.8 macro for most cameras, 60mm f/2.8 Nikkor macro for Nikon bodies without a drive motor, and Olympus Zuiko 50mm f/2.0 for Four Thirds and Micro Four Thirds bodies). To insure that the hair detail we use for making critical judgements about camera noise processing and detail rendering is in sharp focus at the relatively wide aperture we're shooting at, the focus target at the center of the scene is on a movable stand. This lets us compensate for front- or back-focus by different camera bodies, even those that lack micro-focus adjustments. This does mean, though, that the focus target itself may appear soft or slightly out of focus for bodies that front- or back-focused with the reference lens. We know this; if you click to view the full-size image for one of these shots and notice that the focus target is fuzzy, you don't need to email and tell us. :-) The focus target position will have been adjusted to insure that the rest of the scene is focused properly.

Noise Reduction Oddity. We noticed (along with a few readers) a peculiar behavior for the high ISO noise reduction settings in the Sony A550 (and A500). The Normal setting smudges the red leave pattern in our Still Life target setting more than the High setting. The High setting does reduce chroma noise compared to the Normal setting though (lower crops), and we confirmed the filenames are correct. You may want to leave the A550 high ISO NR setting at High for this reason, but be aware that continuous mode burst speed may be impacted.

Extremes: Sunlit and low light tests
Very high resolution with excellent highlight and shadow detail. Good low-light performance, capable of capturing bright images in near darkness, however manual exposure was required and autofocus struggled at lower light levels.

Sunlight:
The Sony Alpha 550 handled the deliberately harsh lighting in the test above very well. Though contrast is a little high, shadow and highlight detail are both very good. The camera's contrast adjustment also did a good job of decreasing overall contrast without producing strong color variations; see the section below. The +1.0 EV exposure did the best job here, as the model's face was a bit too dim at +0.7 EV and we felt that too many highlights were lost at +1.3 EV. These shots were captured with the Sony A550's DRO (Dynamic Range Optimizer) control set to its default of "Auto." This seemed to help quite a bit with both exposure accuracy and highlight/shadow preservation on this difficult shot. Be sure to use fill flash in situations like the one shown above; it's better to shoot in the shade when possible.

Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here.)

Contrast Adjustment
We really like it when a camera gives us the ability to adjust contrast and saturation to our liking. It's even better when those adjustments cover a useful range, in steps small enough to allow for precise tweaks. Just as with its saturation adjustment, the Sony A550's contrast setting meets both challenges.

At its lowest contrast setting, the A550 did a really excellent job of preserving highlight detail, maintaining natural-looking skin tones, and holding nice detail in the shadows. The A550 captures good color outdoors, though just slightly on the warm side. Overall, very good results here, especially when the contrast setting is tweaked. (This is a really tough shot; the Sony A550 does a much better than average job handling it.)

The series of shots above shows results with several different contrast adjustment settings, showing the minimum step size around the default, as well as both extremes. While you can see the extremes, it's hard to really evaluate contrast on small thumbnails like these, click on any thumbnail to go to the full-size image.

One very nice feature of Sony's contrast adjustment is that it has very little effect on color saturation. Contrast and saturation are actually fairly closely coupled, it's a good trick to be able to vary one with out the other changing as well. Sony did a good job here.

Dynamic Range Optimization is Sony's name for their dynamic range enhancement technology. DRO divides the image into small areas, analyzes the range of brightness of each area, and adjusts the camera's image processing parameters accordingly to make the best use of the available dynamic range. Auto DRO is enabled by default on the Sony A550. You can also set the level manually, from 1 ("weak") to 5 ("strong"), or turn it off.

The above images and crops show the effects of DRO disabled, set to Auto (the default), Level 1 ("weak") and Level 5 ("strong") for our "Sunlit" Portrait shot with +1.0 EV exposure compensation. As you can from the crops, Auto DRO had only a slight effect on the highlights in this shot, with higher levels clipping just slightly more highlights The bulk of the difference between different levels of DRO is found in the shadow areas. The stronger the level, the more boost is applied to the shadows. Along with that boost is an increase in shadow noise, though noise is not as much of an issue as we expected for a 14-megapixel subframe sensor.

High Dynamic Range. The Sony A550's HDR mode takes two images in rapid succession, one nominally exposed (or underexposed), and one overexposed, then combines them into one high dynamic range image automatically. Lighter areas from the nominally exposed image are combined in-camera with darker areas from the overexposed image to produce an image with increased dynamic range. The camera then saves a single composite image. The overlaid images are micro-aligned by the camera, but it can only correct for so much movement. If it can't micro-align successfully, an icon indicating HDR capture failed will appear. The user manual warns that for best results, the subject should not move or blink, so it's not really intended for portraits. There is also a manual mode where you can select 1 EV ("weak") to 3 EV ("strong") difference in exposures. As you can see, the Auto setting produced an image that looks a little flat and unnatural with this scene. Highlights remained about the same for all settings, probably because very few were blown in the first place. The lowest manual setting of 1 EV did a great job at boosting shadows without additional noise. In fact, shadow noise is lower since the overexposed image would have less noise in the shadows than the nominally exposed image. There may also be some blending going on, which would also average out random noise. 

Face Detection
Just like most Point & Shoot cameras these days, the Sony A550 has the ability to detect faces in Live View mode, and adjust exposure and focus accordingly. Up to eight faces can be detected at once. As you can see from the examples above, it really works, as the image with face detection enabled is much better exposed for the face, even though both images were shot without any exposure compensation.

Low light. The Sony A550 was able to capture bright images at the lowest light level with the lowest sensitivity setting (ISO 200), but required the use of manual exposure mode. The A550's auto exposure (metering) did not work well at all at lower light levels, resulting in very underexposed images. Noise is quite low up to ISO 800, and at higher ISOs noise grain is pretty fine, but chroma noise gets a little blotchy. There's no sign of any banding issues or uncorrected hot pixels. Color balance looked good with the Auto white balance setting, though chroma noise impacts the color of darker midtones and shadows at higher ISOs.

The camera's autofocus system was able to focus on the subject down to just below the 1/4 foot-candle light level unassisted. This is a rather poor performance for an SLR, though the A550 was able to focus in complete darkness with the AF assist enabled. Since the Sony A550 doesn't use contrast detection for Live View, low-light AF performance was identical in Live View mode. Keep in mind that the longer shutter speeds here demand the use of a tripod to prevent any blurring from camera movement, Sony's SteadyShot not withstanding. (A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)

How bright is this? The one foot-candle light level that this test begins at roughly corresponds to the brightness of typical city street-lighting at night. Cameras performing well at that level should be able to snap good-looking photos of street-lit scenes.

NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) Digital SLRs like the Sony A550 do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.

Print Quality
Excellent 13x19-inch prints at ISO 200; ISO 800 shots are better at 11x14; and ISO 12,800 images produce usable 5x7-inch prints.

The Sony A550 produces a slightly soft 16x24-inch print, such that we'd say it's better starting at 13x19 inches. This is something of an upset, as the lower-resolution Sony A500 achieves a sharper 16x24-inch print, something worth noting, and likely due to the greater noise suppression needed for the Sony A550's 14-megapixel sensor.

ISO 400 shots look quite good at 13x19 inches, with good color and detail.

ISO 800 images start to lose some detail at 13x19 inches, especially among the reds, which start to blur dramatically thanks to noise suppression. The prints are still usable, but some low-contrast reds could start to be a problem. Printing at 11x14 inches looks quite a bit better.

ISO 1,600 shots continue to be usable at 11x14 inches, though some very fine detail starts to smudge. Reds are still very fuzzy, a trend that continues as ISO rises.

ISO 3,200 images print better at 8x12, with good color and detail.

ISO 6,400 images are a little softer, but are still usable at 8x12 inches.

ISO 12,800 files look pretty good at 5x7, and even sharper at 4x6.

Overall its a good performance from the Sony A550, but still not quite up to par with the A500. Careful RAW conversion could still get more detail from these 14-megapixel files, however. But if you're shooting JPEGs only, you'll get slightly more detail with the Sony A500.

Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon Pro9000 Mark II studio printer, and on the Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)