Sony A900 Image Quality
Sony A900 Exposure
Saturation & Hue Accuracy
Accurate color and saturation, with only minor shifts in hue and intensity.
Skin tones. Here, with the color balanced properly for the light source, the Alpha A900's skin tones looked natural, but perhaps just slightly on the warm side. 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 900 showed only a few small color shifts relative to the correct mathematical translation of colors in its subjects, but had pretty good accuracy overall. Most noticeable was a shift in reds toward orange, and yellow toward green, with some shifts in cyans and blues as well, but overall hue accuracy was very good. Hue is "what color" the
The Sony A900 has a total of seven saturation settings available (only five are shown below), 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. (So if you find the A900's default color rendering a little understated for your tastes, it will be quite easy to boost it one or two notches to better match your personal preferences.)
|Saturation Adjustment Examples|
The table above shows results with several saturation settings, see the Thumbnails index page for more (look for the files named A900OUTBSATx.JPG). Click on any thumbnail above to see the full-sized image.
| See full set of test images
See thumbnails of all test and gallery images
Exposure and White Balance
Indoors, incandescent lighting
Good color with both the Manual and 2,600 Kelvin white balance settings, but very warm results with Auto and slightly warm with Incandescent. Slightly above average positive exposure compensation required.
|Auto White Balance
|Incandescent White Balance
|Manual White Balance
|2,600 Kelvin White Balance
Indoors, under normal incandescent lighting, the Sony Alpha 900 produced very warm color with its Auto white balance setting. (This isn't the first camera we've said this about: We expect better automatic white balance handling in a $3,000 camera.) The Incandescent setting wasn't too far off the mark; just warm enough to suggest the color of the original light source, without seeming overdone. Both the Manual and 2,600-degree Kelvin settings produced more accurate results. It was a bit of a toss-up between them, as the Manual setting was a hint warm and the Kelvin option a little more true to white value. Though the Manual setting did preserve a touch of the original mood, the 2,600-degree Kelvin mode produced the most accurate overall color. The +0.7 EV positive exposure compensation required for this shot was slightly above average. (This new indoor scene usually requires about +0.3 EV exposure compensation.) Color looks good throughout the frame, with only the slightest purplish tints in the blue flowers. (Many digital cameras reproduce these flowers with a dark, purplish tint, so the Alpha 900 actually performs a little better than average here.) 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.
Very good results under harsh lighting, with good handling of contrast, detail, and color.
|Auto White Balance,
|Auto White Balance,
Outdoors, the Sony Alpha A900 performed well, but at its default contrast setting required +1.3 EV exposure compensation for the Portrait to avoid rendering the model's face too dark. Even with that much positive exposure compensation though, the A900 did a surprisingly good job of holding onto highlight detail: While the highlights in the mannequin's shirt will appear blown on many computer monitors, close inspection in Photoshop or other editing software reveals that very few areas are actually blown out. Despite the high contrast (as you might expect under such harsh lighting), the camera did a better than average job of holding onto detail in both the deep shadows and bright highlights. The Sony A900 nailed the exposure in the House shot, and managed not to blow out many highlights at all, or lose shadow detail in the process. Color balance is good as well, with good saturation considering the bright lighting. 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 does change slightly). Overall, a very good performance.
Extremely high resolution, 2,200 lines of strong detail.
|1x chart: Strong detail to
>2000 lines horizontal
|1x chart: Strong detail to
>2000 lines vertical
|2X chart: Strong detail to
2,200 lines horizontal
(multiply values by 2)
|2X chart: Strong detail to
2,200 lines vertical
(multiply values by 2)
Our laboratory resolution chart revealed sharp, distinct line patterns down to about 2,200 lines per picture height in the horizontal direction as well as in the vertical direction. Complete extinction didn't occur within 4,000 line limit of our 2x chart, but lines began to merge at about 2,800 lines per picture height. 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.
Sharpness & Detail
Sharp, very detailed images, though minor edge-enhancement artifacts visible on high-contrast subjects. Minor noise suppression visible at low ISO.
Sharpness. The Sony Alpha 900 produced amazingly detailed images, with good sharpness. Some slight edge enhancement artifacts are visible on high-contrast subjects such as the crop above left, but overall results are still very good. 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 only minor noise suppression artifacts, as the darker areas of the model's hair show a lot of detail. Individual strands are still distinguishable even in the lighter shadows, though they begin to merge as shadows deepen. Still, good performance here, especially considering the 25-megapixel sensor. 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 A900 does a pretty good job at balancing between sharpness and visible sharpening artifacts in its in-camera JPEGs. You can often find a fair bit more detail in carefully-processed RAW files than is evident in the camera-generated JPEGs. 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. Examples include in-camera Extra-Fine JPEG, a RAW file processed through Sony's Image Data Converter SR version 3 software at default settings, another IDC version converted at lowest sharpening, then sharpened in Photoshop, and finally an Adobe Camrea Raw 4.6 beta version, then sharpened in Photoshop. (When shooting RAW+JPEG, the A900 will only save a Fine JPEG, which is why the Extra Fine JPEG and RAW crops aren't identical.) As we've seen in the past, Image Data Converter SR doesn't extract a whole lot more detail than the camera itself does, but we see a bit more detail from an Adobe Camera Raw converted file, though noise is also more visible.
ISO & Noise Performance
Low noise at ISO 100 through 400. Effects of noise reduction visible from ISO 800 up.
|ISO 100||ISO 200||ISO 400|
|ISO 800||ISO 1,600||ISO 3,200|
The Sony Alpha A900 produced low noise at its lower sensitivity settings, however we start to see some slight smudging and loss of detail already at ISOs as low as 400. As you'd expect, noise and loss of detail becomes more apparent at ISO 800, with noise "grain" becoming increasingly courser, along with some chroma noise in the shadows. At ISO 1,600, along with increased detail loss, the chroma noise becomes more obvious and no longer relegated to just deep shadows. ISO 3,200 continues this trend with even more detail loss and blotchiness, and ISO 6,400 is quite noisy with chroma noise and blurring almost entirely obliterating fine detail. There is also a slight desaturation of images at ISOs 3,200 and 6,400. Keep in mind that these are 25-megapixel files, though, so detail loss won't be nearly as apparent at normal print sizes. See the Print Quality section to find out what the recommended maximum size print is at each ISO setting.
Extremes: Sunlit and low light tests
High resolution and good shadow detail. Very good low-light performance, capable of capturing bright images in near darkness.
|+0.7 EV||+1.0 EV||+1.3 EV|
Sunlight. The Sony Alpha A900 handled the deliberately harsh lighting in the test above pretty well. Though contrast is a little high, highlight detail is good and shadow detail very good. The camera's contrast adjustment also did a good job of decreasing overall contrast without producing strong color variations. A higher-than-average +1.3 EV exposure compensation was required to keep the model's face from looking too dark, as the +1.0 EV exposure was a touch too dim. This resulted in a few lost highlights in the model's shirt and in some of the flowers, but not as much as we're accustomed to seeing. 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.)
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 A900's contrast setting meets both challenges.
|Minimum Contrast, normal D-R setting (Off)|
|Contrast set to lowest,
|Contrast set to lowest,
At its lowest contrast setting, the A900 did an excellent job of preserving highlight detail, maintaining natural-looking skin tones, and holding nice detail in the shadows. The A900 captures good color outdoors, though just slightly on the warm side. Overall, very good results here, especially when the contrast setting is tweaked.
|Contrast Adjustment Examples|
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.
Sony's DRO (Dynamic Range Optimization)
Sony's Dynamic Range Optimization system analyzes the range of brightness of each image, and adjusts the camera's image processing parameters accordingly, to try make the best use of the available dynamic range. Three options are available on the A900: DRO Off, Standard DRO, and Advanced DRO+. Unlike lesser Sony SLRs, the A900's default for DRO is Off. The A900 also allows you choose the strength for the Advanced DRO+ effect, from level 1 to 5. Standard DRO looks at the entire image and effectively adjusts contrast and brightness across the entire image for best effect. Advanced DRO+ analyzes everything, but makes local adjustments to bring out shadow detail and preserve highlights.
|DRO Off||DRO Standard||DRO+ Advanced
The crops above show the results of three DRO settings. As you can see, the bulk of the difference between different levels of DRO is found in the shadow areas, though the Advanced setting with its localized adjustments also improved highlight preservation. By default, the Sony A900 shoots with DRO set to Off. (Previous models defaulted to DRO Standard mode.) Interestingly, there's a pretty pronounced difference between DRO Standard or Advanced Level 5 and Off, in terms of exposure. We confirmed that the shots above were all captured with the same aperture and shutter speed settings, but the DRO Standard version is 2/3 of a stop or so lighter than the shot with DRO turned off entirely, a behavior we saw with the A200, A350 and A700 as well. Still, the DRO-enabled shots have fewer clipped highlights than the DRO Off shot with a simple exposure boost applied to bring the shadows up to the same level.
Low light. The Sony A900 performed very well on the low-light test, capturing usable images at the lowest light level even at the lowest sensitivity setting (ISO 100). The above images are all a little dim at the default exposure, but consistently so, allowing the use of exposure compensation or manual mode to brighten them up by using longer shutter speeds. Color balance looked quite good with the Auto white balance. Noise was fairly low up to ISO 400, but as expected, became more noticeable with higher ISOs, especially with noise reduction turned off. There were also hot pixels visible at ISO 1,600 and above at lower light levels. The camera's autofocus system was able to focus on the subject almost down to the 1/16 foot-candle light level unassisted (and in complete darkness with the AF assist enabled). Keep in mind that the longer shutter speeds here demand the use of a tripod to prevent any blurring from camera movement. (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 A900 do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.
Great print quality, good color, sharp 20x30-inch prints from RAW files, usable ones from in-camera JPEGs.
The Sony A900's printed output was quite impressive, able to output sharp 20 x 30 inch prints from its RAW files at ISO 200, and good-looking ones that size from its in-camera JPEGs. As of this writing in early September, 2008, the only RAW converter that can read the A900's images is Sony's own Image Data Converter. We processed the RAW images in that, but with the sharpening set to zero, then transferred the 16-bit TIFF image into Photoshop, where we applied unsharp masking at 250% and 0.3 pixel radius. The result was a good bit sharper detail than that in the camera-generated JPEGs, but we suspect we'll see more yet once Adobe Camera RAW and other third-party RAW converters can read the Sony A900's files.
With 25 megapixels of resolution, there's plenty of detail in the Sony A900's images to go larger than 20x30 inches: We tried outputting a part of our Far Field test image at the equivalent of 30 x 40 inches. Even with the careful unsharp masking in Photoshop, the result was a little soft looking, but would absolutely be suitable for display at typical viewing distances for prints that large. (It looked quite sharp when viewed at any distance greater than two to three feet.) What actually limited the usable print size more than detail was image noise: At 30x40 inches (which is really pretty huge), noise in the sky and flat shadow areas was quite visible, even at ISO 200, the camera's native sensitivity.
As noted elsewhere in this review, the Sony A900 has higher resolution than any other 35mm format DSLR, but the Canon EOS-1D Mark III wins handily in terms of image noise. We're reluctant to refer to this as the A900's "Achilles heel," particularly in light of the fact that the 1Ds Mark III sells for 2.6x the price of the A900. It is, though, one of the most noticeable areas in which the A900 falls short of its much more expensive competitor, so deserves mentioning.
Checking print quality at higher ISOs, we found that the Sony A900's images produced good-looking 13x19 inch prints up to about ISO 400 or 800: Minor chroma noise began to appear at ISO 400, and became more prominent at ISO 800, although many users would probably find the ISO 800 results at 13x19 inches suitable for wall display. At 5x7 inches, images looked good to ISO 1,600 and usable to ISO 3,200.
Color-wise, we found the Sony A900's images very appealing. Given the relatively understated color handling we observed in the Imatest results, we somewhat expected to find the printed output a little dull-looking, but this wasn't the case: Colors looked plenty bright, but never unnatural. Very nice color, overall.
Bottom line, the Sony A900 is a camera that can deliver incredible resolution under good to moderate lighting, and as such should find application for commercial work, portraits, landscapes, architectural and fine art photography and similar applications. At the highest magnifications though, some noise is visible even at its default ISO 200 sensitivity, and this steadily increases as you go up the ISO scale. As always, the obtrusiveness of its image noise varies inversely with the size of the print you're making. If all you care about is 8x11 output, you'll probably find the Sony A900 usable up to ISO 1,600 and possibly higher. On the other hand, we expect that a large part of the reason many people will plunk down $3,000 for this camera is because they want to exploit its extraordinary resolution by making really large prints. If that's your application, then the maximum useful ISO drops quite a bit, to the extent that ISO 800 is really pushing it, even for 13x19 inch prints. We say "even for 113x19 inch prints" because, while that size is about as large as most prosumer inkjet printers go, it's not that big compared to the A900's 25 megapixel resolution. (At 300 pixels/inch, the A900's output would measure 13.4x20.2 inches.)
While we haven't been able to test one yet, a good third-party RAW converter and aftermarket noise-processing software package could give you considerably more ISO headroom. Barring that, the A900 is really best used at ISO 400 and under, at least for those times when you'll want to print to 13x19 inches or larger.
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 studio printer, and on the Canon iP5200 here in the office. (See the Canon PIXMA Pro9000 review for details on that model.)
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