Canon 7D Image Quality
Canon 7D Image Quality
Saturation & Hue Accuracy
Very good saturation and hue accuracy.
Skin tones. Flesh tones shot with the Canon 7D appeared quite natural, with appropriate saturation levels and accurate color, though slightly on the cool side. When white-balance was adjusted to match the lighting, skin-tones were warmer, with a "healthy looking glow". 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 Canon 7D's hue accuracy is quite good, just a hair less accurate than the 50D. There were the usual shifts in cyan toward blue, red toward orange, and orange toward green, but they are pretty minor. Excellent hue accuracy overall. Hue is "what color" the
The Canon 7D offers a total of nine saturation settings, four above and four below the default saturation. This covers a very wide range of saturation levels, about as wide a range as you're likely to find photographically useful, apart from special effects that are arguably better achieved in software. As it should, the 7D's saturation adjustment affects only the saturation, leaving the contrast of the image more or less unaltered. (In some cameras, saturation tends to affect contrast, and vice versa.) The fine steps between settings mean you can program the camera to just the level of saturation you prefer. Well done.
|Saturation Adjustment Examples|
The table above shows results with the default as well as the two extreme saturation settings. Click on any thumbnail above, then click again to see the full-sized image.
Exposure and White Balance
Indoors, incandescent lighting
Auto and Incandescent settings both struggle somewhat with household incandescent lighting, though Manual and 2,600 Kelvin white balance settings produce much more neutral images. Slightly above average exposure compensation required.
|Auto White Balance
|Incandescent White Balance
|Manual White Balance
|2,600 Kelvin White Balance
Indoors, under incandescent lighting, the Canon 7D's Auto white balance setting really struggled to produce a decent-looking image. Unfortunately, this is quite common among cameras we've tested, but disappointing nonetheless, particularly in a premium-grade enthusiast/professional SLR.
The Canon 7D's Incandescent setting did a little better, but the resulting image was still a little warm for our tastes. (Some may feel that it successfully conveys the warmth of the original lighting, but we'd personally like a slightly more neutral treatment.) This is undoubtedly correct for a camera aimed at professionals, whose incandescent studio lighting is generally balanced to 3,200 Kelvin. Note, too, that the Canon 7D's white balance system permits very flexible manual adjustment of each of its presets, so the Incandescent setting could easily be tweaked to match the requirements of household lighting of the type used here.
The Manual and 2,600 Kelvin white balance options were very similar, both producing fairly neutral images. Manual white balance was the most accurate, with the 2,600 Kelvin setting being just a touch cool. The Canon 7D required a positive exposure compensation of 0.7 EV for this shot, a little higher than the +0.3 EV 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.)
Color and saturation are very good, though a tendency towards slightly cool color balance and slightly high contrast under harsh lighting. About average exposure accuracy.
|Auto White Balance,
|Auto White Balance,
Outdoors, the Canon 7D tended toward a slightly cool color balance, as you can see by the skin tones in the above left shot, though overall color was generally excellent. The Canon 7D performed about average in terms of exposure, requiring the typical amount of positive compensation we're accustomed to seeing among digital cameras. The Canon 7D's default contrast is a little high, producing some washed-out highlights and dark shadows under the deliberately harsh lighting of our "Sunlit" portrait test shown above left, though the camera's contrast and highlight tone priority settings do help tame the highlights quite a bit. See below for examples of this. The far-field house shot (above right) was also a touch cool, though exposure was quite accurate, with relatively few blown highlights or lost shadows.
Very high resolution, 2,000 ~ 2,100 lines of strong detail.
|Strong detail to
2,100 lines horizontal
|Strong detail to
2,000 lines vertical
|Strong detail to
2,100 lines horizontal
ACR Converted RAW
|Strong detail to
2,000 lines vertical
ACR Converted RAW
Our laboratory resolution chart showed the Canon 7D's images with sharp, distinct line patterns down to about 2,100 lines per picture height horizontally and 2,000 lines vertically. Extinction occurred at about 3,100 lines in both directions. We weren't able to do much better with Adobe Camera Raw converted .CR2 files. 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
Good sharpness and loads of detail. Some detail loss to noise reduction processing even at low ISOs, but surprisingly good for an 18-megapixel subframe sensor.
Sharpness. The Canon 7D's 18-megapixel sensor captures loads of image detail. Some minor edge-enhancement artifacts are visible around high-contrast edges, as shown in the crop above left. (The above crop of our far-field house shot was taken with Canon's very sharp 16-35mm f/2.8L II USM lens at f/8, as the 28-135mm kit lens is somewhat soft.) 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 some detail loss due to noise suppression, but less than we're accustomed to seeing, and perhaps even less than the Canon 50D, which has larger photosites than the 7D. Very impressive. 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 mentioned above, the Canon 7D does an excellent job of capturing sharp detailed JPEGs when coupled with a sharp lens, but as is usually the case, slightly more detail can be preserved by carefully processing its RAW files.
In the table above, mousing over a link at the bottom will load the corresponding crop in the area above, and clicking on the link will load the full resolution file. Examples include in-camera Fine JPEG, RAW file processed through Canon's Digital Photo Professional (DPP) software using default settings, another DPP processed RAW file with no sharpening in DPP, but sharpened in Photoshop, and finally, a RAW file processed through Adobe Camera Raw (ACR) version 5.6, then sharpened in Photoshop.
For the Canon EOS 7D's images, I found best results with 400% unsharp masking with an 0.3 pixel radius for the unsharpened DPP converted file, and 300% unsharp masking with an 0.3 pixel radius for the ACR converted file.
Manufacturer software often doesn't find as much detail as does Adobe Camera RAW, but Canon's DPP does better than most. The image processed through ACR does however show a little more detail, as well as more noise. The Canon 7D is clearly a camera that carries a lot of data in its RAW files.
ISO & Noise Performance
Low noise and excellent detail at the lowest ISO settings, ISO 1,600 is very usable for average print sizes. Noise vs detail performance very good for the resolution, and noise processing is generally improved over that of the EOS 50D.
Default High ISO Noise Reduction
|ISO 100||ISO 200||ISO 400|
|ISO 800||ISO 1,600||ISO 3,200|
|ISO 6,400||ISO 12,800|
The Canon 7D's images are quite clean at ISOs 100 and 200, with just a bit luminance noise seen in the shadows. We start to see a very fine, tight "grain" pattern at ISO 400, but detail is hardly affected, with no signs of chroma noise. The grain is slightly more evident at ISO 800, but detail remains very strong. At ISO 1,600, we begin to see some moderate detail loss as noise reduction blurs subtly contrasting detail, but results are still quite good. At ISO 3,200, noise grain becomes coarser and the blurring stronger, resulting in a noticeable drop in detail. Noise and the effects of noise reduction really become apparent at ISO 6,400 and especially at ISO 12,800, with strong blurring, bright noise pixels and chroma blotching. That said, the 7D's noise reduction processing generally does a bit better job of preserving fine detail than that of the 50D, and it shows far fewer hot pixels at ISOs 6,400 and 12,800 than the 50D did. Overall, an excellent performance, particularly for a camera with an 18-megapixel APS-C size sensor.
We're of course pixel-peeping to an extraordinary extent here, since 1:1 images on an LCD screen have little to do with how those same images will appear when printed. See the Print Quality section below for our evaluation of maximum print sizes at each ISO setting.
A note about focus for this shot: We shoot this image at f/4, 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. 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 about it; we already know it. :-) The focus target position will simply have been adjusted to insure that the rest of the scene is focused properly.
Extremes: Sunlit and low light tests
Very high resolution with strong overall detail, but slightly high default contrast. Highlight Tone Priority and contrast adjustment options do a great job of dealing with tough lighting, though, and highlight and shadow detail are very good even without them. Good low-light performance, though metering and autofocus struggled at the lowest light levels.
|+0.3 EV||+0.7 EV||+1.0 EV|
The Canon EOS 7D produced slightly high contrast with some washed-out highlights and deep shadows under the deliberately harsh lighting of the test above. However, highlight and shadow detail are actually pretty good. The model's face was a little dim at the +0.3 EV setting, so we preferred the image with +0.7 EV of exposure compensation, which resulted in some clipped highlights in the shirt and flowers, mostly in the blue and red channels, but not as much as we're used to seeing without some sort of dynamic range optimization setting (see below). Compensation of +1.0 EV resulted in a too many clipped highlights for our tastes, though some shooters may prefer the brighter image for its better skin tones.
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.)
Highlight Tone Priority Example
Shadow Detail, R.H.S. Brightened in Photoshop
(Levels control, highlight slider down to 50)
Highlight Tone Priority
The Canon 7D's Highlight Tone Priority (HTP) option did an excellent job of preserving highlight detail, as shown above, though it rendered the model's face a little too dim. (In hindsight, it would have been better to shoot this series with more positive exposure compensation, as there wasn't much highlight clipping to begin with.) Both shots above were captured at the same +0.3 EV exposure, the only difference being that HTP was enabled for the shot on the right. (Which necessarily increases the ISO to 200, part of how HTP works.) The result is evident even in the histograms and thumbnails above; the full-size images clearly show the superior highlight preservation when HTP is enabled, while shadow detail is left relatively untouched. The right side of the Shadow Detail crops above have had their histogram levels adjusted equally in Photoshop to reveal the increase noise in the HTP-On case. The increase in noise is because the ISO is boosted from 100 to 200. Except in the very deepest shadows, though, overall noise is so low at ISO 200 that this is really a negligible trade-off for all but the most critical applications.
|Contrast Adjustment Examples|
The Canon 7D's contrast-adjustment control also does an excellent job with very difficult lighting like this. It offers a very broad range of control in usefully fine gradations, and does a good job of adjusting contrast without affecting color saturation in the process. (As noted earlier regarding saturation adjustment, something that not all cameras manage to do.) For those interested, here are some additional links showing this same shot taken with intermediate settings of Contrast -2 and Contrast +2.
|Automatic Lighting Optimization Examples|
Automatic Lighting Optimization
Like the Canon 50D, the Canon EOS 7D offers three selectable levels of ALO, plus Off. In fully automatic and Creative Auto exposure modes, ALO is automatically enabled. All four shots above were taken with the same exposure settings. As you can see, ALO has the effect of shifting shadows and mid-tones in the histograms to the right, lightening the overall image without clipping too many additional highlights.
|Off at 0 EV||On at 0 EV|
Just like most Point & Shoot cameras these days, the Canon 7D has the ability to detect faces in Live View mode, and adjust exposure and focus accordingly. As you can see from the examples above, it really works, as the image with face detection enabled is much better exposed for the face, even though both images were shot without any exposure compensation.
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.)
Low light. The Canon 7D performed reasonably well on the low-light test, capturing bright images at the lowest light level (1/16 foot-candle), even with the lowest sensitivity setting (ISO 100). However, the camera's exposure metering system struggled a bit at lower light levels, so manual exposure was used for the above images. As expected, noise increases as ISO goes up and light levels go down, but remains surprisingly low up to ISO 1,600, though there are a few bright pixels at ISO 1,600 at lower light levels. At ISO 3,200 and above, noise is higher and bright pixels appear more frequently, but there is very little if any of the horizontal banding that we saw from the EOS 50D at high ISOs. Color balance was pretty neutral with Canon 7D's Auto white balance setting, even at high ISOs and lower light levels.
The Canon 7D's phase-detect autofocus system was able to focus on the subject to just below 1/8 foot-candle light level unassisted, and in complete darkness with the AF assist enabled. That's not quite as good as most semi-pro SLRs. (The Canon 50D's AF system could focus unassisted to less than 1/16 foot-candle.) We were hoping the production-level Canon 7D would improve over the prototype in that regard, but unfortunately, it didn't. In Live View mode, the 7D's contrast-detect autofocus was able to focus down just below the 1/4 foot-candle level without assistance. That's fairly typical for contrast-detection AF.
As always, 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 Canon 7D do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.
Exceptional print quality, good color, very sharp 24 x 36 inch prints from both JPEG and RAW. Exceptional print quality at all high ISOs as well.
Though we normally judge prints from JPEG for this section, we were curious how RAW images would look, and since the Canon 7D is a professional camera, we first took a brief look at ISO 100 RAW. We found the best results through DPP at low ISOs with noise reduction turned off, sharpening set to zero, and then using unsharp masking after the fact in Photoshop, with a radius of 0.3 pixels and strength of 400%. The results were pretty phenomenal when printed at 24 x 36 inches. Crisp is indeed the correct word. Here's a link to a sample of our Still Life target, shot at ISO 100 and processed with that formula. It's a 13.6MB JPEG, so be patient with the download.
Getting back to the JPEGs, the Canon 7D at ISO 100 can produce a very good 24 x 36-inch print. It's a little softer than the tack-sharp image we got from RAW, but it can also be sharpened for better results. The same is true from ISO 200.
ISO 400 produces a very good 20 x 30 print.
At ISO 800, a reduction to 16 x 20 inches is needed, and there is some minor noise in flatter areas, but not too bad.
ISO 1,600 shots are good at 11 x 14 inches, also quite remarkable, though low-contrast reds start to have some trouble thanks to noise suppression.
ISO 3,200 shots are good at 8 x 10 inches, with the exception of low-contrast reds, which we'll stipulate for the rest of the settings.
ISO 6,400 shots retain decent detail for printing at 5 x 7 inches, but shadows begin to darken and the image increases in contrast overall.
ISO 12,800 shots darken more, and chroma noise comes in, such that 5 x 7-inch prints are usable, but not great. Reducing the image size to 4 x 6, though, looks good, with light grain and hardly noticeable chroma noise.
Overall it's a pretty amazing performance.
Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon Pro9000 Mark II studio printer, and on the Canon Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)
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