Sony A7S Exposure

Saturation & Hue Accuracy
Saturation generally increases with ISO, with typical hue accuracy.

Saturation. The Sony A7S's mean default color saturation is 113.2% at base ISO or in other words, oversaturated by 13.2%. That's just a bit above average these day, but unusually, mean saturation actually increases with sensitivity, reaching a peak of 119.5% at ISO 204,800. Cameras often reduce saturation at higher ISOs to reduce the appearance of chroma noise, but the A7S bucks that trend. As usual, reds and dark blues are boosted the most, but not as much as we often see. Most other colors are pushed just a bit, though yellow, light green and aqua are slightly undersaturated which is quite common. Overall, saturation levels are quite pleasing to our eyes, and you can of course tweak saturation to your liking. 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. The Sony A7S does fairly well with Caucasian skin tones when white balance is adjusted to match the lighting. Brighter flesh tones have a healthy-looking pinkish tint, though darker areas are nudged slightly toward orange. Still, pretty good results here. 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. Like many cameras, the Sony A7S pushes cyan toward blue, red toward orange, orange toward yellow and yellow toward green, but shifts are relatively minor. (The cyan to blue shift is actually fairly minor and 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 5.1 after correction for saturation at base ISO, overall hue accuracy is about average, with accuracy only moderately lower at higher ISOs. Hue is "what color" the color is.

Exposure and White Balance

Indoors, incandescent lighting
Warm color with Auto white balance; Incandescent is pretty good, and Manual is very good. Slightly above average exposure compensation required.

Indoors, under normal incandescent lighting, color balance is too warm and orange with the Auto white balance setting. Results with the Incandescent setting are quite good, though, and only slightly warm, while the Manual setting is the most accurate. The Sony A7S required +0.7 EV positive exposure compensation here, which is slightly above the average of +0.3 EV required for this shot. (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
Excellent results under harsh lighting, with very good handling of contrast, color, and exposure.

Outdoors, the Sony A7S performed very well. +0.7 EV exposure compensation was required to keep the mannequin's face reasonably bright in our "Sunlit" Portrait shot, which is average among the cameras we've tested. Contrast is a little high as you might expect under such harsh lighting, but the camera did a great job of holding onto bright highlights and detail in the shadows, even without the help of Sony's Dynamic Range Optimization (DRO) feature. We preferred Manual color balance for the "Portrait" shot though, as Auto white balance produced skin tones that were a touch warm and yellow. Default exposure is just slightly underexposed in our Far-field shot (above right), but with very few highlights blown or shadows lost, again with DRO disabled. The Far-field shot with Auto white balance has very good color, perhaps just a touch warm. Overall, great performance in harsh lighting, especially considering DRO was off for these shots.

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

Resolution
Moderate resolution (by today's standards); ~2,100 lines of strong detail from JPEGs, about the same from RAW files.

In-camera best quality JPEGs of our laboratory resolution chart reveal sharp, distinct line patterns down to about 2,100 lines per picture height in the horizontal direction and to about 2,100 lines per picture height in the vertical direction. Some may argue for higher numbers, but aliasing artifacts and false colors start to interfere at this resolution, making it a difficult call. Complete extinction of the pattern didn't occur until about 2,700 lines in both directions. Adobe Camera Raw wasn't really able to extract more resolution here from a RAW file, but it produced more color moiré as it often does. 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
Excellent sharpness, with few sharpening artifacts. Mild noise suppression visible in the shadows and areas of low contrast.

Sharpness. The Sony A7S captures very sharp, crisp images overall, and it doesn't leave behind heavy sharpening halos around edges with high contrast that we often see, such as around the lines and letters of our olive oil bottle label crop (above left). Excellent results here. 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 relatively mild noise suppression in the darker areas of the mannequins's hair. Only a small number of low-contrast strands are smudged together, while higher contrast strands remain distinct. Excellent results here as well. 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 A7S produces in-camera JPEGs with sharp, crisp detail. Additional detail can often be obtained from carefully processing RAW files with a good converter, so let's have a look:

In the table above, we compare a best quality in-camera JPEG taken at base ISO using default noise reduction and sharpening (on the left) to the matching RAW file converted with Adobe Camera Raw 8.6 with some strong but tight unsharp masking applied in Photoshop (250%, radius of 0.3 pixels, and a threshold of 0).

As you can see, the Adobe Camera Raw conversion does contain more fine detail, especially in the red-leaf swatch which so many cameras struggle with. And because the Sony A7S produces very low noise levels, there's almost no additional noise to be seen when using ACR's default noise reduction, which is often not the case. Although the A7S does a very good job at rendering most of the available detail without many sharpening artifacts (at least at base ISO), discerning users will likely still want to shoot in RAW mode to get the most out of the A7S's sensor (as well as a lot more latitude for post-processing).

ISO & Noise Performance
Outstanding high ISO performance.

The Sony A7S's in-camera JPEG images are very clean and detailed at ISOs 50 through 800, with almost no degradation in image quality as ISOs increase within this range. ISOs 1600 through 12,800 show a nice, progressive decline in image quality, with pretty good detail left at 12,800 for such a high ISO. At ISO 51,200, luma noise starts to become prominent, chroma noise more noticeable, and image quality drops off rapidly from there, with the top two ISOs looking more like Monet paintings than photographs. Still, outstanding high ISO performance.

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 since the scene isn't brightly lit as it's in typical indoor lighting. 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 crop area of the scene is focused properly.

Extremes: Sunlit, dynamic range and low light tests
Excellent highlight and shadow detail in harsh lighting. Very good low-light performance, capable of capturing bright images in near darkness.

Sunlight. The Sony A7S handled the deliberately harsh lighting in the test above very well. We preferred the +0.7 EV exposure here, as the +0.3 EV exposure is a touch dim in the face while the +1.0 EV exposure was oddly the same brightness (with manual white balance; Auto white balance was brighter, yet used the same exposure variables). Contrast is a little high, but shadow and highlight detail are both excellent. Despite the bright appearance, few highlights are blown in the mannequin's shirt and face at +0.7 EV, though the red channel is clipped in some of the flowers as is often the case, as well as in specular highlights where you'd expect clipping. There are some dark shadows however they're very clean, though very deep shadows are posterized as expected. Overall, excellent performance here.

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 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 A7S. 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 on the right to load the associated thumbnail and histogram, and click on the link to visit the full resolution image. As you can see from the thumbnails and histograms, increasing DRO progressively boosts shadows and midtones while leaving highlights essentially intact. The Auto setting did a pretty good job overall especially when compared to the default exposure without it, and the five manual levels give quite a bit of control over the effect.

Above, you can see the effect of DRO settings on our Far-field shot. The default Auto setting produced a nicely balanced exposure, despite the harsh lighting. A useful feature.

High Dynamic Range. The Sony A7S'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 compressed tonal 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 the camera can't micro-align successfully, an icon indicating HDR capture failed will appear. For best results, the subject should not move or even 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 link to visit the full resolution image. As you can see, the Auto setting did a pretty good job, with an effect somewhere between the 2 and 3 EV manual settings. The higher the manual setting, the more highlights were toned-down and shadows opened up, but as you can see higher settings can produce flat and unnatural results with this subject.

Above, you can see the effect of HDR settings on our Far-field shot. Watch out for ghost images from subject movement during the capture sequence, though, as can be seen in some of the shots above. Still, Sony has one of the better in-camera HDR implementations we've seen.

Dynamic Range Analysis (RAW mode). While we once performed our own dynamic range measurements based on in-camera JPEGs as well as converted RAW images (when the camera was supported by Adobe Camera Raw), we've switched to using DxO Labs' results from their DxOMark website. As technology advanced, the dynamic range of modern high-end cameras in some cases exceeded the range of the Stouffer T4110 density scale that we used for our own measurements. DxO's approach based on RAW data before demosaicing is also more revealing, because it measures the fundamental dynamic range of the sensor, irrespective of whatever processing is applied to JPEGs, or to RAW data by off-the-shelf conversion software.

In the following, we use DxO's "Print" dynamic range results, which are scaled based on camera resolution. As the name suggests, this scaling corresponds to the situation in which you print at a given size, regardless of how many megapixels the camera might have. (In other words, if you've decided to make a 13x19 inch print, that's the size you're printing, whether the camera's resolution is 16 or 300 megapixels.) For the technically-minded, you can find a discussion of the reasoning behind this here on the DxOMark website. Also note that DxO Labs uses a signal-to-noise (SNR) threshold of 1 when defining the lower boundary of acceptable luminance noise in their dynamic range measurements, which corresponds to the "Low Quality" threshold of the Imatest software we used to use for this measurement.

Here, we compare the 12-megapixel Sony A7S to its sibling the 24-megapixel A7, as well as to the 16-megapixel Nikon Df which is considered one of the best full-frame DSLRs for low light photography. The graph above is interesting, as it shows the Sony A7 provides significantly better dynamic range at base ISO, with the A7 managing 14.01 EV versus the A7S's 13.16 EV and the Df's 13.09 EV. But keep in mind this is Printed dynamic range, so the A7's significantly higher resolution puts it at an advantage when printed at the same size, since the higher resolution camera will have more of its noise averaged out when downsampled during the normalizing process. (And indeed, if we compare the "Screen" results, we'll see the A7's dynamic range drop down to values much closer to the A7S at base ISO.)

As expected, where the Sony A7S really shines is at high ISOs, where it offers an advantage of up to about 1.8 f-stops (9.05 EV vs 7.25 EV @ ISO 25,600 ) over the A7, and just over a one stop advantage over the Df at the same ISO. Remarkable. Click here to visit the DxOMark page for the Sony A7S for more of their test results and additional comparisons.

Low Light. The Sony A7S performed extremely well in our low light tests, producing bright images down to the lowest light level we test at (1/16 fc). Noise is practically nonexistent at ISO 100, and very low at ISO 3200. Some very fine luma and chroma noise can be seen at ISO 3200 with noise reduction minimized (right-most column), however it has a tight "grain" which isn't objectionable. As expected, noise is very high at the highest ISO of 409,600. We didn't notice any significant issues with hot pixels or heat blooming, and perhaps just some faint banding (pattern noise) at the highest ISOs.

Auto white balance did a very good job here, producing a fairly neutral, just slightly cool color balance.

The Sony A7S's autofocus system was able to focus on our target down to below the 1/16 foot-candle light level unassisted with an f/2.8 lens. That's excellent for a mirrorless camera, and we can probably attribute that to the A7S's larger-than-average photosites. And with the AF-assist lamp enabled the Sony A7S also focused below the 1/16 foot-candle level. Assisted low-light autofocus performance will of course vary with subject type and distance, but the Sony A7S was able to focus in very dim conditions without assistance, albeit much more slowly than in bright conditions.

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. (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.)

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 its larger sensor, compact system cameras like the Sony A7S tend to do better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.

Print Quality

Excellent prints as large as 24 x 36 inches from base up to ISO 400; an impressive 20 x 30 at ISO 800; and an acceptable 4 x 6 all the way up to ISO 51,200.

ISO 100 through 400 images look practically the same with excellent detail, color and, as expected, zero to extremely low noise, and therefore all print up to a maximum size of 24 x 36 inches. At this resolution, we are pushing the limits of the 12MP sensor, and at close inspection, you can see some pixelation. However at normal viewing distances of an arm's length or farther, images look nice and crisp.

ISO 800 prints are very similar to the lower ISO prints, however there is a very slight increase in shadow noise, and as such, the safe bet is a maximum 20 x 30 print size. That being said, you could probably get away with the next size larger in certain situations.

ISO 1600 images look practically identical to ISO 800 shots -- with the same level of fine detail and color rendition -- and therefore also print to 20 x 30 inches.

ISO 3200 prints as large as 16 x 20 inches as they start to show a bit more noise than the previous two ISO levels, though the increase in noise is primary restricted to shadow areas. Fine detail is still very good, even in notoriously difficult areas such as our red fabric.

ISO 6400 images are again slightly noisier than the previous ISO, but noise is overall very well-controlled for this ISO level and therefore can make prints up to 13 x 19 inches quite easily.

ISO 12,800 prints can go as large as 8 x 10 inches with no sweat. While noise is stronger now, it’s still confined primarily to the shadows and overall looks pretty fine-grained at this print size. Colors are still pleasant at this ISO as well.

ISO 25,600 images are getting into tricky territory now with stronger noise, making a 5 x 7 inch print the largest we feel comfortable giving our stamp of approval to.

ISO 51,200 prints max out at 4 x 6 inches. The noise is rather strong at this level and colors are looking less appealing with a slight greenish tint.

ISO 102,400 - 409,600 images, while impressive to exist in the first place, are nonetheless too noisy and lacking in fine detail to call any print size acceptable.

Despite having a rather meager 12-megapixel resolution by today's standards, the full-frame Sony A7S manages some impressive print sizes at lower ISOs. Pushing the resolution of the sensor, ISO 100-400 files can all print up to a maximum size of 24 x 36 inches. While you see some pixelation at very close inspection, from a normal viewing distance for such a size, the prints are crisp, detailed and display nice, pleasing colors. At the higher ISOs of 3200 and 6400, the A7S manages solid 16 x 20 and 13 x 19 inch prints, respectively. Noise is well-controlled at these ISOs, mainly confined to shadow areas, and colors still look great. While the Sony A7S is touted for its insanely high maximum ISO of 409,600, usable prints nevertheless top out around ISO 51,200 with a 4 x 6 inch print.