Sony A7 Exposure
Sony A7 Image Quality
Saturation & Hue Accuracy
Typical saturation levels and hue accuracy.
|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 and click on links for larger images.|
Saturation. The Sony A7's mean default color saturation is 111.2% at base ISO or in other words, oversaturated by 11.2%. That's about average these days. Saturation remains fairly consistent across the ISO range, dropping just slightly as sensitivity rises. Reds, dark blues and dark green 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 A7 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 A7 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 5.17 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.
The Sony A7 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. Saturation also has little effect on contrast, which is how it should work.
|Saturation Adjustment Examples|
The table above shows results with five of the seven saturation settings, including the default and the two extremes. 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
Exposure and White Balance
Indoors, incandescent lighting
Warm cast with Auto white balance; Incandescent is pretty good, and Manual is very good; too cool with the Kelvin setting. Average exposure compensation required.
|Auto White Balance
|Incandescent White Balance
|Manual White Balance
Indoors, under normal incandescent lighting, color balance is a bit too warm and orange with the Auto white balance setting, though results here are slightly better than average. Results with the Incandescent setting are quite good and only slightly warm. Results with the Manual setting are the most accurate. The 2,600 Kelvin setting which should match the color temperature of our lights is too cool and bluish. The Sony A7 required +0.3 EV positive exposure compensation here, which is about average 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.)
Excellent results under harsh lighting, with very good handling of contrast, color, and exposure.
|Manual White Balance,
|Auto White Balance,
Outdoors, the Sony A7 performed very well. +0.7 EV exposure compensation was required to keep the mannequin's face bright in our "Sunlit" Portrait shot, which is average among the cameras we've tested. (Actually, in fully automatic mode, exposure is bright without any compensation so the A7 performs better than average here in full Auto mode.) Contrast is a little high as you might expect under such harsh lighting, but the camera does a great job of holding onto detail in both the shadows and bright highlights, even without the help of DRO. We preferred Manual color balance for the "Portrait" shot though, as Auto white balance produced skintones that were a touch too warm and yellow. Default exposure is just slightly underexposed in our Far-field shot, 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, just a touch cool. Overall, great performance in harsh lighting, especially considering DRO was off for these shots.
Very high resolution, ~2,850 to ~2,900 lines of strong detail from JPEGs, about the same from RAW files.
|Strong detail to
~2,900 lines horizontal
|Strong detail to
~2,850 lines vertical
|Strong detail to
~2,900 lines horizontal
ACR converted RAW
|Strong detail to
~2,850 lines vertical
ACR converted RAW
In-camera JPEGs of our laboratory resolution chart reveal sharp, distinct line patterns down to about 2,900 lines per picture height in the horizontal direction and to about 2,850 lines per picture height in the vertical direction. Some may argue for higher numbers, but aliasing artifacts start to interfere at this resolution. Complete extinction of the pattern didn't occur until about 3,600 lines in both directions. (Interestingly, the Sony A7 leaves more color moiré in the JPEG than its AA-filter-less sibling the A7R. Perhaps Sony thought the A7 doesn't need to suppress it since it has an optical low-pass filter, albeit an obviously weak one.) Adobe Camera Raw wasn't really able to extract more resolution here from matching RAW files, but it produced a lot 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.
Sharpness & Detail
Excellent detail and sharpness, with very few sharpening artifacts (at low ISOs). Mild noise suppression visible in the shadows and areas of low contrast.
|Excellent definition of
high-contrast elements with very low sharpening artifacts.
|Subtle detail: Hair
Noise suppression tends to blur
detail in areas of subtle contrast.
Sharpness. The Sony A7 captures very sharp, crisp and detailed images overall, and it doesn't leave behind heavy sharpening halos around edges with high contrast that we often see around the lines and letters of our bottle label crop (above left), at least not at low ISOs. The A7's RAW images don't need a lot of sharpening because of the weak optical low pass filter, but Sony really has done an excellent job with the A7's JPEG processing as well, at least at low ISOs. 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 fairly mild noise suppression in the darker areas of the model's hair. A number of low-contrast strands are smudged together, though higher contrast strands are distinct, though as you can see some suffer from the "jaggies" (see below). Still, excellent results here considering the resolution. 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.
As you can see in the crop on the right, there are odd demosaicing errors in our mannequin's hair as well as the "jaggies" (jagged edges) in some individual strands. In our Still Life shots (see crops below), moiré patterns can be seen in the red-leaf fabric, and you can see moiré in some other shots as well, such as in the artificial roses of our Indoor Portrait test shots and in some of our gallery shots.
With the increasing trend of using either a very weak or no optical low pass filter, quite a few cameras produce similar artifacts these days, but it's still something to be aware of especially if you shoot a lot of man-made subjects with repeating patterns, such as buildings, fabrics, etc. Techniques than can be used to reduce aliasing include shooting at a smaller aperture so that lens diffraction acts as an anti-alias filter, defocusing slightly, shooting at higher ISOs, and post-processing particularly with RAW files.
RAW vs In-Camera JPEGs
As noted above, the Sony A7 produces in-camera JPEGs with lots of crisp detail. Additional detail can often be obtained from carefully processing RAW files with a good converter, but the A7's JPEG processing is some of the best we've seen from a camera, at least at lower ISOs.
In the table above, we compare an 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 8.3 using default noise reduction with some strong but tight unsharp masking applied in Photoshop (200%, radius of 0.3 pixels, and a threshold of 0).
As you can see, the Adobe Camera Raw conversion contains more fine detail, even revealing some of the threads in our challenging red-leaf fabric, but it also reveals a bit more luminance noise in flat areas. You can always turn up the luminance noise reduction (default of zero was used here), though. Also note the moiré pattern in the red-leaf pattern in both images, as sign that the A7's anti-alias filter is quite weak.
Bottom line: Although Adobe Camera Raw is able to extract a bit more detail, the Sony A7's JPEG engine does a fantastic job at low ISOs, with a great balance of fine, crisp detail, low noise, and low sharpening artifacts straight out of the camera.
ISO & Noise Performance
Excellent detail versus noise tradeoff up to ISO 3200.
Default High ISO Noise Reduction
|ISO 50||ISO 100||ISO 200|
|ISO 400||ISO 800||ISO 1600|
|ISO 3200||ISO 6400||ISO 12,800|
The Sony A7's JPEG images are quite clean and extremely detailed at ISOs 50 though 400, with just minor smudging in the shadows and in areas of low contrast and a tiny drop in image quality as ISO rises. As mentioned previously, there are demosaicing errors in the hair above the mannequin's forehead and some individual strands of hair exhibit the jaggies, but surprisingly there's no color moiré in the jacket where we normally expect to see it from cameras with weak (or no) OLPFs. You can however see a little luminance moiré in the artificial roses. ISO 800 is slightly softer though fine detail is still excellent. ISO 1600 is the first sensitivity step that shows any significant blurring of fine detail, but detail retention is still very good. ISO 3200 is softer as you'd expect, however fine detail is still good, but images start to take on a more processed, almost painted look in flat areas. ISO 6400 still contains some fine detail but flatter areas start to look a bit crunchy with more obvious noise reduction artifacts. ISO 12,800 is significantly noisier and sharpening combined with strong noise reduction give the image a somewhat crystalline look, while abrupt tonal transitions and edges look rough and haloed. Chroma noise also starts to become an issue with purple and yellow blotches in the hair, though overall, chroma noise is still well controlled. Almost all fine detail in the hair is lost at ISO 25,600 and high contrast edges are very rough and strongly haloed with obvious noise reduction, sharpening and possibly compression artifacts. Chroma noise is more obvious as well.
Overall, though, very good noise versus sensitivity performance that's competitive with other full-frame models of similar resolution, though noise reduction processing could be a bit more refined at higher ISOs. (We'd prefer a more natural looking film-like grain instead of the cleaner but over-processed look, especially from this class of camera.) 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
Very high resolution with excellent highlight and shadow detail. Very good low-light performance, capable of capturing bright images in near darkness.
|+0.3 EV||+0.7 EV||+1.0 EV|
Sunlight. The Sony A7 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 is a bit too bright. Contrast is a little high, but shadow and highlight detail are both very good. Despite the bright appearance, few highlights are blown in the model's shirt and face at +0.7 EV, though the red channel is clipped in some of the flowers as is often the case, and in specular highlights where you'd expect clipping. There are some dark shadows however they're pretty clean, though very deep shadows are posterized as expected. Overall, excellent performance here.
For best results, 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.)
|Aperture Priority, 0 EV
Face Detection Off
|Aperture Priority, 0 EV
Face Detection On
Face Detection. Like most cameras these days, the Sony A7 has the ability to detect faces (up to 8 in a scene), and adjust exposure and focus accordingly. As you can see from the examples above, face detection didn't work as expected in Aperture Priority at f/8, producing a darker image than without it. Full Auto mode worked well, though, where the camera had control over aperture and automatically applied DRO. Nice.
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 A7's contrast setting meets both challenges.
|Contrast set to lowest,
|Contrast set to lowest,
At its lowest contrast setting, the A7 does a really excellent job of toning down highlights and opening up shadows while maintaining fairly natural-looking skin tones. Very good results here.
|Contrast Adjustment Examples|
The table above shows five of the seven contrast setting, 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.
The Sony A7's contrast adjustment has only a minor effect on color saturation. Contrast and saturation are actually fairly closely coupled, it's a good trick to be able to vary one without the other changing as well.
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 A7. 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 associated histograms, increasing DRO progressively boosts shadows and midtones while leaving highlights essentially intact, though boosting shadows does make noise slightly more visible. The Auto setting did a pretty good job overall, 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 A7'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 it 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, similar to the 4 EV manual setting. 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 Sony A7 to the Nikon D610 and Canon 6D full-frame DSLRs. As you can see from the above graph (click for a larger image), the A7's dynamic range compares fairly nicely to the D610's, ranging from a maximum of about 14 EV at base ISO down to 7.3 EV at maximum ISO. The Sony A7's dynamic range is up to about 2/3 EV less than the Nikon D610's at lower ISOs, but is practically identical at ISO 1600 and higher. The A7's dynamic range is however dramatically better than the 6D's at lower ISOs with an almost 2 EV advantage at base ISO, though at ISO 3200 and above, the Canon pulls ahead of both cameras with up to a ~0.8 EV advantage compared to the A7. Bottom line, though, the Sony A7's dynamic range in RAW data across ISOs is excellent. Click here to visit the DxOMark page for the Sony A7 for more of their test results and additional comparisons.
Low Light. The Sony A7 performed well in our low light tests, producing usable images down to the lowest light level we test at (1/16 fc) at all ISO settings, though ISO 50 at the lowest light level is a little dim because of the 30 second shutter speed limit (bulb mode can be used for longer exposures, though). Noise is well-controlled up to ISO 6400, though as expected, at higher ISOs there are moderate amounts of fine luminance noise especially around edges as well as some blotchy chroma noise in darker areas. With noise reduction minimized (right-most column), noise "grain" is quite fine and tight and not too objectionable except at the highest ISOs. (Apologies for some slightly soft images, manual focus seems to have shifted slightly during the series.)
We found a few hot pixels, particularly when long exposure noise reduction is turned off (where you'd expect to find them), but nothing significant. We didn't detect any significant issues with banding, however some minor heat blooming can be seen emanating from the bottom of the frame in longer exposures at the highest ISOs. That's not unusual, though.
Auto white balance did a very good job here, producing a fairly neutral, just slightly cool color balance.
The Sony A7's autofocus system was able to focus on our target down to just above the 1/8 foot-candle light level unassisted with an f/2.8 lens. That's fair for a mirrorless, and not nearly as good as most DSLRs. And with the AF-assist lamp enabled the Sony A7 needed 1/2 foot-candle to autofocus in our tests, because the bright AF-assist lamp overwhelmed the camera's autofocus system. This of course will vary with subject type and distance.
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 and Hybrid AF, compact system cameras like the Sony A7 tend to do better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.
|Low Light (1 foot-candle) Multi-frame NR|
|Default NR, 1/125s, ISO 25,600||Multi-frame NR, 1/125s, ISO 25,600|
Multi-frame Noise Reduction. This feature is similar to Sony's Hand-held Twilight mode which shoots a burst of four images with a single press of the shutter button and combines all four 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. (We frankly don't see the value to this mode when using a tripod, as selecting a lower ISO and longer shutter speed will produce a cleaner image as well.) As you can see, the image captured with Multi-frame Noise Reduction (right) is cleaner than the standard image (left) despite both being shot at ISO 25,600. An added bonus is that ISO 51,200 equivalent is available with MF NR. As with HDR mode, though, static subjects are recommended.
Excellent 36 x 48 inch prints at ISO 50/100; ISO 3200 images look good at 13 x 19; ISO 12,800 images make a good 5 x 7.
ISO 200 and 400 prints look superb at 30 x 40 inches, with excellent detail, nice color, and no trace of noise or noise suppression artifacts.
ISO 800 images look quite good at 24 x 36 inches, with only the slightest hint of noise in flatter areas and mild softening in reds. 20 x 30's are fantastic here and eliminate virtually all of these minor concerns.
ISO 1600 shots show a slight pattern of luminance and chrominance noise in the shadows, but you have to look closely to make it out, even at 20 x 30 inches, which is a nice size for this ISO. Detail is still quite sharp except for our tricky red swatch, which is typical for most cameras to have trouble with. 16 x 20s tighten up a lot more and are superb here.
ISO 3200 prints at 13 x 19 inches start to show a light grain pattern in the shadows, with reds becoming a bit softer. We can still give this size our "good" rating, but for ultra-critical prints at this ISO you'd be better to remain at 11 x 14 inches.
ISO 6400 images almost make the grade at 11 x 14, but there is just a bit too much noise in flatter areas with default noise reduction to call them "good". Certainly OK for less critical applications, but we can call 8 x 10s good here, which is still a nice size print for ISO 6400.
ISO 12,800 prints will work for less critical applications at 8 x 10 inches and almost warrant the "good" seal, which is really amazing. 5 x 7's are quite good for most any application, and colors still look nice, retaining good overall saturation for this ISO.
ISO 25,600 prints are a bit on the soft side in general, but will work for a decent 4 x 6, which is not bad!
The Sony A7 certainly delivers the goods in the print quality department, as expected. At base ISO, 36 x 48 inch prints look outstanding indeed, and while not of the super-crisp caliber of the 36mp big brother A7R, they're still world class and among the best for this resolution of 24 megapixels. There is a noticeable downturn in quality and a rise in noise beginning at ISO 3200, but it's nice to know that even at ISO 6400 you can still achieve a good quality 8 x 10 inch print. And good for Sony for producing a decent print even at the highest rated ISO!
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Sony Alpha ILCE-A7 Photo Gallery .
Not sure which camera to buy? Let your eyes be the ultimate judge! Visit our Comparometer(tm) to compare images from the Sony Alpha ILCE-A7 with those from other cameras you may be considering. The proof is in the pictures, so let your own eyes decide which you like best!
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