Sony Alpha A99

• 
• Review contents
• Pro shooter's report
• Design & tech overview
• Image quality & test shots
• Performance results
• Video results
• Final conclusion
• Discuss the A99

Sony A99 Image Quality

by Zig Weidelich

On this page:
Color
Sensor
Resolution
Sharpness & Detail
ISO & Noise Performance
Extremes: Sunlit, dynamic range and low light tests
Print Quality

Color

Saturation & Hue Accuracy

Typical saturation levels at lower ISOs, with about average hue accuracy. Saturation increases at higher ISOs while hue accuracy decreases.

Saturation

Like a lot of cameras, the Sony A99 pumps strong reds and dark blues moderately, pushes darker orange, greens, purples and browns just a little, but undersaturates yellow, aqua and cyan tones slightly. The A99's mean color saturation of 111.1% (11.1% oversaturated) at base ISO is just a touch higher than average for a professional SLR, though the camera allows you to tweak saturation to your liking, or choose a different color mode. Saturation remains fairly consistent up to ISO 1,600, but actually increases at higher ISOs, up to 122% at ISO 25,600. 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.

ISO Sensitivity
50	100	200	400	800
1600	3200	6400	12800	25600
In the diagram above, the squares show the original color, and the circles show the color that the camera captured. More saturated colors are located toward the periphery of the graph. Hue changes as you travel around the center. Thus, hue-accurate, highly saturated colors appear as lines radiating from the center. Mouse over the links to compare ISOs.

Skin tones

Here, when adjusted for the correct white balance, the Sony A99 did well, producing natural-looking lighter Caucasian skin tones with a pink tint, though darker skin tones show a slight push toward orange. 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 Sony A99 shifts cyan toward blue, red toward orange, orange toward yellow and yellow toward green, but shifts are relatively minor. (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.) With an average "delta-C" color error of 5.36 after correction for saturation, overall hue accuracy is fairly typical, perhaps just slightly lower than average for a professional DSLR at base ISO. Hue accuracy decreases slightly as ISO increases, with delta-C color error peaking at 6.27 at the maximum ISO. Hue is "what color" the color is.

Saturation Adjustment

The Sony A99 has a total of seven saturation settings available, three above and three below the default saturation. 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. Saturation also has little effect on contrast, which is what you want.

Saturation Adjustment Examples
-3	-1	0	+1	+3

The table above shows results with the seven saturation settings. Click on any thumbnail above, then click again to see the full-sized image.

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

ISO & Noise Performance

Very good noise versus detail performance up to ISO 3,200.

ISO Series (Default High ISO Noise Reduction)
ISO 50	ISO 100	ISO 200
ISO 400	ISO 800	ISO 1,600
ISO 3,200	ISO 6,400	ISO 12,800
	ISO 25,600

ISOs 50 through 200 are very clean and almost identical in terms of noise. At ISO 400, we see a touch of softening due to stronger noise reduction, but images still have excellent detail. ISOs 800 through 1,600 show progressively less detail along with incremental levels of noise, however detail remains very good. ISO 3,200 shows a slightly larger decline in image quality with more visible noise and noise-reduction artifacts, though detail is still good and chroma noise well controlled. ISO 6,400 starts to look a little rough on screen, with stronger luminance noise and more obvious sharpening artifacts, though there's a moderate amount of fine detail left intact. Chroma noise in the form of yellow blotches is more noticeable and shadows and midtones. ISO 12,800 and especially 25,600 images contain quite a bit of luminance noise and much stronger noise reduction which obliterates fine detail. There's also a lot of chroma noise in the form of yellow and purple blotches, particularly in shadows. We don't however see the usual drop in saturation at high ISOs, which is a nice surprise.

Overall, very good high ISO performance, if not quite as good as some recent full-frame rivals. 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.

Multi-frame Noise Reduction
Default NR, 1/2000s, ISO 12,800	Multi-frame NR, 1/2000s, ISO 12,800

Multi-frame Noise Reduction

This feature is similar to Sony's Hand-held Twilight mode which shoots a burst of six images with a single press of the shutter button and combines all six images into one composite image with reduced noise. But unlike Hand-held Twilight, Multi-frame NR gives you control over the ISO, aperture and shutter speed used, so you may still need to use a tripod depending on the exposure parameters you select. As you can see above, the image captured with Multi-frame Noise Reduction (right) is much cleaner than the standard image (left) despite both being shot at ISO 12,800, but it's also quite a bit softer. Multi-frame NR images do look better with some extra sharpening applied, though, and an added bonus is that ISO 51,200 equivalent is available for JPEGs (raw files are not supported).

ISO 1,600 High ISO NR = "Off"	ISO 1,600 High ISO NR = "Normal"

Noise Reduction Oddity

The Sony A99's "Off" High ISO NR setting smudges the red leaf pattern in our Still Life target much more than the "Normal" or "Low" settings at higher ISOs. The Normal setting does reduce both chroma and luminance noise compared to the Off setting, though (lower crops). We've seen similar behavior with older Sony Alpha models such as the A55/A35/A33 and NEX-5/3, but not with more recent models. We have confirmed this happens with v1.0 firmware.

Extremes: Sunlit, dynamic range and low light tests

Very high resolution with very good dynamic range. Very good low-light performance, capable of capturing bright images in near darkness.

0 EV	+0.3 EV	+0.7 EV

Sunlight

The Sony A99 handled the deliberately harsh lighting in the test above very well. We preferred the +0.3 EV exposure here, as the mannequin's face was a little dark at default exposure, and too bright at +0.7 EV. Contrast is a little high, but highlight detail is actually very good. Despite the apparent brightness, there are very few clipped highlights in the model's face and shirt. There are some pretty deep shadows though, but a lot of detail is intact except in the very deepest. Overall, very good results here. Still, be sure to use fill flash in situations like the one shown above; it's better to shoot in the shade when possible. See below for results with Dynamic Range Optimization and High Dynamic Range features enabled.

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. In actual shooting conditions, be sure to use fill flash in situations like the one shown here; it's better to shoot in open shade whenever possible.)

Dynamic Range Analysis

A key parameter in a digital camera is its Dynamic Range, the range of brightness that can be faithfully recorded. At the upper end of the tonal scale, dynamic range is dictated by the point at which the RGB data "saturates" at values of 255, 255, 255. At the lower end of the tonal scale, dynamic range is determined by the point at which there ceases to be any useful difference between adjacent tonal steps. Note the use of the qualifier "useful" in there: While it's tempting to evaluate dynamic range as the maximum number of tonal steps that can be discerned at all, that measure of dynamic range has very little relevance to real-world photography. What we care about as photographers is how much detail we can pull out of the shadows before image noise becomes too objectionable. This, of course, is a very subjective matter, and will vary with the application and even the subject matter in question. (Noise will be much more visible in subjects with large areas of flat tints and subtle shading than it would in subjects with strong, highly contrasting surface texture.)

What makes most sense then, is to specify useful dynamic range in terms of the point at which image noise reaches some agreed-upon threshold. To this end, Imatest computes a number of different dynamic range measurements, based on a variety of image noise thresholds. The noise thresholds are specified in terms of f-stops of equivalent luminance variation in the final image file, and dynamic range is computed for noise thresholds of 1.0 (low image quality), 0.5 (medium image quality), 0.25 (medium-high image quality) and 0.1 (high image quality). For most photographers and most applications, the noise thresholds of 0.5 and 0.25 f-stops are probably the most relevant to the production of acceptable-quality finished images, but many noise-sensitive shooters will insist on the 0.1 f-stop limit for their most critical work.

JPEG dynamic range

The graph at right (click for a larger version) was generated using Imatest's dynamic range analysis for an in-camera Sony A99 JPEG file with a nominally-exposed density step target (Stouffer 4110). At the base ISO of 100 (the optimal ISO in our tests) with DRO and HDR settings turned off, the graph shows 11 f-stops of total dynamic range, and 7.87 f-stops at the "High" Quality level. Roll-off is gradual at the highlight end of the tone curve, though the shadow end is quite abrupt, and the last two steps are spread out, indicative of a tendency of the deepest shadows to break up into discrete levels if you try to brighten them too much. Those steps are extremely deep shadows though, so it's really not much of a concern. Overall, these are are very good results for in-camera JPEGs, though not quite as good as the best we've seen to date. The Nikon D600 for example managed 9.12 f-stops at the High Quality level, however total dynamic range was identical at 11 f-stops. Note that this measurement has a margin of error of about 1/3 f-stop, so differences of less than 0.33 can be ignored when comparing to other models.

Raw dynamic Range

The graph at right is from the same Stouffer 4110 stepchart image captured as a Raw (.ARW) file, processed with Adobe Camera Raw using the Auto setting, then manually tweaked. As can be seen, the score at the highest quality level increased from 7.87 to 9.7 f-stops, which is almost a two f-stop improvement, while total dynamic range increased 1.8 f-stops, from 11 to 12.8. The High Quality result is excellent, though again not quite as good as the best sensors we've tested. (The Nikon D600 for example scored 10.5 f-stops at the highest quality level, and 13.1 total.) It's worth noting here is that ACR's default noise reduction settings reduced overall noise somewhat (see the plot in the lower left-hand corner) relative to the levels in the in-camera JPEG, which would tend to boost the dynamic range numbers for the higher quality thresholds.

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 A99's contrast setting meets both challenges.

Minimum Contrast
Contrast set to lowest, 0 EV	Contrast set to lowest, 0 EV

At its lowest contrast setting, the A99 did a really nice job of opening up shadow detail while maintaining natural-looking skin tones. Overall, very good results here. (This is a really tough shot; the Sony does a much better than average job handling it.)

Contrast Adjustment Examples
-3	-1	0	+1	+3

The table above shows five of the seven contrast settings, including the default and two extremes. It's pretty hard to evaluate small differences in contrast on small thumbnails like these, so click on any thumbnail to go to the full-size image.

Sony's contrast adjustment has some effect on color saturation, though not much. Contrast and saturation are actually fairly closely coupled, so it's a good trick to be able to vary one with out the other changing as well.

Outdoor Portrait DRO Comparison
	DRO Setting: Auto (Default) Off Level 1 Level 2 Level 3 Level 4 Level 5

Dynamic Range Optimization

is Sony's name for their single exposure 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 A99. You can also set the level manually, from 1 ("weak") to 5 ("strong"), or turn it off. As one would expect, DRO is only available for JPEG files.

The above thumbnails and histograms show the effects of the various levels of DRO on our "Sunlit" Portrait shot with no exposure compensation. Mouse over the links to load the associated thumbnail and histogram, and click on the links to visit the full-resolution image. As you can see from the thumbnails and associated histograms, DRO had only a slight effect on the highlights in this shot, though few highlights were clipped to begin with. The bulk of the difference between different levels of DRO is found in the shadows and darker midtones. The stronger the DRO level, the more boost is applied to darker areas. Boosting shadows does reveal a bit more noise, but the A99's noise levels at low ISOs are low enough that this shouldn't be an issue for most applications. The default Auto DRO setting did a pretty good job here, producing a fairly well-balanced image compared to Off.

Far-field DRO Comparison
Auto (default)	Off	Level 1	Level 2
Level 3	Level 4	Level 5

Above, you can see the effect of DRO settings on our Far-field shot. The default Auto setting again produced a good exposure overall, despite the harsh lighting.

Outdoor Portrait HDR Comparison
	HDR Setting: Off (Default) Auto 1 EV 2 EV 3 EV 4 EV 5 EV 6 EV

High Dynamic Range

The Sony A99's HDR mode takes three images in rapid succession, one nominally exposed, one underexposed, and one overexposed, then combines them into one high dynamic range JPEG automatically. Lighter areas from the underexposed 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, as well as the nominally exposed 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. 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 6 EV ("strong") difference in exposures.

Mouse over the links to load the associated thumbnail and histogram, and click on the links to visit the full-resolution image. As you can see, the highest settings produce images that looked flat and unnatural with this scene, however Auto and the lower manual settings did a pretty good job at boosting shadows. reducing highlights, while still retaining enough contrast.

Far-field HDR Comparison
Off (default)	Auto	1 EV	2 EV
3 EV	4 EV	5 EV	6 EV

Above, you can see the effect of HDR settings on our Far-field shot. Notice the ghosting of the flags or people

	1 fc 11 lux	1/2 fc 5.5 lux	1/4 fc 2.7 lux	1/8 fc 1.3 lux	1/16 fc 0.67 lux	1/16fc No NR
ISO 50	4 s f2.8	8 s f2.8	15 s f2.8	30 s f2.8	30 s f2.8	30 s f2.8
ISO 100	2 s f2.8	4 s f2.8	8 s f2.8	15 s f2.8	30 s f2.8	30 s f2.8
ISO 200	1 s f2.8	2 s f2.8	4 s f2.8	8 s f2.8	15 s f2.8	15 s f2.8
ISO 400	0.5 s f2.8	1 s f2.8	2 s f2.8	4 s f2.8	8 s f2.8	8 s f2.8
ISO 800	1/4 s f2.8	0.5 s f2.8	1 s f2.8	2 s f2.8	4 s f2.8	4 s f2.8
ISO 1600	1/8 s f2.8	1/4 s f2.8	0.5 s f2.8	1 s f2.8	2 s f2.8	2 s f2.8
ISO 3200	1/15 s f2.8	1/8 s f2.8	1/4 s f2.8	0.5 s f2.8	1 s f2.8	1 s f2.8
ISO 6400	1/30 s f2.8	1/15 s f2.8	1/8 s f2.8	1/4 s f2.8	0.5 s f2.8	0.5 s f2.8
ISO 12800	1/60 s f2.8	1/30 s f2.8	1/15 s f2.8	1/8 s f2.8	1/4 s f2.8	1/4 s f2.8
ISO 25600	1/125 s f2.8	1/60 s f2.8	1/30 s f2.8	1/15 s f2.8	1/8 s f2.8	1/8 s f2.8

Low Light

The Sony A99 performed well in our low light test, producing bright images down to the lowest light level we test at (1/16 foot-candle) at all ISO settings, though ISO 50 is a bit dim at the lowest light levels because of the 30 second limit in shutter speed (there is a bulb mode for longer exposures). Noise is well controlled up to ISO 3,200, though as expected, at higher ISOs there are moderate to high amounts of luminance noise and some blotchy chroma noise.

Auto white balance did a pretty good job here, producing a slightly cool color balance at most ISOs and light levels, though dark colors took on a greenish cast at higher ISOs and lower light levels.

We didn't detect any issues with stuck or hot pixels (except when long exposure noise reduction is turned off, where you'd expect to see them), and only some very minor horizontal banding is visible at very high ISOs, but that's not uncommon. Some minor heat blooming emanating from the bottom edge is visible at highest ISOs, but again, that's normal at extreme ISOs.

The Sony A99's autofocus system was able to focus on the subject down to the 1/16 foot-candle light level unassisted with an f/2.8 lens, and in complete darkness with AF assist enabled. This is very good performance, though some DSLRs are able to autofocus below 1/16 foot-candle without AF assist.

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.) Thanks to their phase-detect AF systems, digital SLRs like the Sony A99 tend to do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects. (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.)

Print Quality

Excellent 30 x 40 inch prints at ISO 50 and 100; stunning 13 x 19 prints at ISO 1,600; and a very good 8 x 10 inch print at 6,400.

ISOs 50 and 100 images are excellent at 30 x 40, with stunning detail and vibrant color. Prints are also quite usable at 36 x 48 with only a few areas showing a slight loss of sharpness. Even the 40 x 60 inch prints will make a nice wall display.

ISO 200 makes terrific 24 x 36 inch and very usable 30 x 40 inch prints.

ISO 400 images look great at 20 x 30, sharp and crisp, with 24 x 36 inch prints still very usable with only minor blurring of certain areas.

ISO 800 is also nice and crisp at 20 x 30, with only minor luminance noise becoming apparent at 24 x 36.

ISO 1,600 starts to see minor loss of definition in our ever-difficult red swatch at 16 x 20, but is still a nice print, and stunning at 13 x 19.

ISO 3,200 shows some grain at 16 x 20, with some noticeable softening in the red channel, but makes for a nice print at 13 x 19 and an excellent one at 11 x 14. Even a 16 x 20 will work here for a wall display.

ISO 6,400 makes an amazingly sharp 11 x 14 print. This is -not- your grandad's DSLR, that's for sure. Minor grain is apparent, but becomes a non-issue for the ever-popular 8 x 10 inch prints.

ISO 12,800 8 x 10s are usable for a wall print, with 5 x 7s quite nice here. Special note for ISO 6,400 and 12,800: if you don't mind a minor boost in grain in the background you can push the size up a level and still get nice saturation and color renditioning.

ISO 25,600 5 x 7s have amazing color for such a super-high ISO, and 4 x 6 inch prints look crisp and clear.

One of the most telling parts of our test target at higher ISOs is the shadowed area on the wall *behind* the test subjects themselves. Manufacturers are doing a better and better job of reducing noise while preserving subject detail, but these shadowed, flat gray areas are very revealing of residual noise, and one of the easiest places to see patchy chroma noise. Even here, though, the Sony A99 excels, easily holding its own against leading competitors in its price and resolution category.

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 the Canon Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)