Canon T3i Image Quality

Saturation & Hue Accuracy
Very good saturation and excellent hue accuracy.

Saturation. The Canon EOS Rebel T3i produces images with near accurate saturation, particularly in the bright yellows, greens and cyans. Strong reds, oranges, dark brown, some greens and dark blues are pushed a little though. The overall saturation of 108% (8% oversaturated) is not too pumped yet not too dull. 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. Lighter flesh tones shot with the Canon Rebel T3i appeared quite natural, with appropriate saturation levels and accurate color, though slightly on the cool side. Darker skin tones show a small shift toward orange. Good results here as well. 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 Rebel T3i's hue accuracy is very good, actually much better than average. There were the usual shifts in cyan toward blue (actually quite small), red toward orange, and orange toward yellow, but all are fairly 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.) Average "delta-C" color error was only 3.39, which is outstanding, being one of the best scores to date. Hue is "what color" the color is.

Picture Style
The Canon EOS Rebel T3i offers six preset "Picture Style" options, plus Auto and three user defined ones. You can adjust Sharpness (0-7), Contrast (+/-4), Saturation (+/-4) and Color Tone (+/-4) for any of the settings. For Monochrome images, you can adjust Filter Effect and Toning Effect instead of Saturation and Color Tone.

Saturation Adjustment
As mentioned above, Canon EOS Rebel T3i 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 Canon T3i'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.

The table above shows alternate settings including 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 with household incandescent lighting, though Manual white balance produced a much more neutral image. Slightly higher than average exposure compensation required.

Indoors, under incandescent lighting, the Canon EOS Rebel T3i's Auto and Incandescent white balance settings both struggled, resulting in very warm color casts. Unfortunately, this is quite common among cameras we've tested, but disappointing nonetheless. The Manual setting produced the most accurate results, though just slightly cool overall. The Canon Rebel T3i required a positive exposure compensation of 0.7 EV for this shot, which is slightly higher than the +0.3 EV average among the cameras we've tested. (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
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.

Outdoors, the Canon EOS Rebel T3i 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 very good. The Canon Rebel T3i performed about average in terms of exposure, requiring the typical amount of positive compensation we're accustomed to seeing among digital cameras. The Canon T3i'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 fairly accurate, with some blown highlights in the white trim but very few lost shadows.

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

Resolution
Very high resolution, 2,000 ~ 2,100 lines of strong detail.

Our laboratory resolution chart showed the Canon Rebel T3i's images with sharp, distinct line patterns down to about 2,000 lines per picture height horizontally and about the same vertically. Extinction of the pattern occurred just past 3,200 lines horizontally and at about 3,000 lines vertically. Adobe Camera Raw converted .CR2 files show slightly more resolution than the in-camera JPEGs, perhaps 100 lines, though complete extinction of the pattern was extended well past 3,200 lines in both directions in the converted files. While ACR was able to extract more detail, it also produced more color moire than JPEGs from the camera, especially in vertical lines. 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
Good sharpness and loads of detail with a sharp lens. Some detail loss to noise reduction processing even at low ISOs.

Sharpness. The Canon EOS Rebel T3i's 18-megapixel sensor captures an excellent level of image detail when coupled with a good lens, though 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.) 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 at this resolution. Very impressive for an 18-megapixel APS-C sensor. (The crop above of the hair taken with our very sharp Sigma 70mm f/2.8 reference lens.) 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 T3i 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 additional sharpening in DPP, and finally, a RAW file processed through Adobe Camera Raw (ACR) version 6.4, then sharpened in Photoshop using 300% unsharp masking with an 0.3 pixel radius.

Canon's DPP software produced images similar to in-camera JPEGs, though at default settings, images were a touch softer than JPEGs from the camera. DPP converted images do however contain a touch more detail as well as fewer sharpening artifacts even when sharpening is turned up to the maximum of 5. Images processed through ACR show even more fine detail than the DPP conversions, but also show more noise at default settings, which is not unusual. You may want to experiment with ACR's noise reduction settings to find the detail vs noise trade-off you're looking for. Regardless, the Canon T3i is clearly a camera that carries a lot of data in its RAW files.

ISO & Noise Performance
Low noise and very good detail at the lower ISO settings, with excellent results up to ISO 800. Noise versus detail performance very good for the resolution.

The Canon EOS Rebel T3i's high ISO performance is pretty good, very similar to the Canon 60D's. Images are quite clean at ISOs 100 and 200, with just a tiny amount of luminance noise seen in the shadows, as well as what looks to be chroma noise in the darker strands of hair. We start to see a very fine, tight "grain" pattern at ISO 400, though detail is hardly affected. (There is some subtle, blotchy chroma noise in deep shadows though.) The grain is slightly more evident at ISO 800, but detail remains very strong despite some minor blurring due to noise reduction. At ISO 1,600 we begin to see some moderate detail loss as noise reduction blurs subtly contrasting detail, as well as more evident chroma noise in darker areas, but results are still quite good. At ISO 3,200 noise grain becomes coarser, blurring stronger and chroma noise more apparent, resulting in a more 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 obvious chroma blotching.

There are also what look to be demosaicing errors in areas of fine vertical detail and high local contrast, such as the strange horizontal bands in the strands of hair on the model's forehead at lower ISOs (see ISO 100 crop at right). We've seen these errors in our indoor portrait JPEG images from other Canon SLRs, as well as hints of it in JPEGs from other manufacturers, so they're not that unusual. The aberrations are very subtle to be sure, but they're something to be aware of if you plan to make very large prints of similar subject matter from JPEGs. They don't appear in RAW files processed with a good converter such as Adobe Camera Raw.

Overall, though, a very good performance. 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, dynamic range and low light tests
Very high resolution with strong overall detail, but somewhat high default contrast and unremarkable dynamic range. Highlight Tone Priority and contrast adjustment options do a great job of dealing with tough lighting. Very good low-light performance.

The Canon EOS Rebel T3i produced moderately high contrast with some washed-out highlights and deep shadows under the deliberately harsh lighting of the test above. The mannequin's face was too dim at the default and +0.3 EV settings, so we preferred the image with +0.7 EV exposure compensation. This resulted in more clipped highlights in the shirt and flowers than we're used to seeing from an APS-C sensor lately, indicating only average dynamic range compared to the best of recent competitors. Shadow detail was however pretty good. While some shooters may prefer the image with exposure compensation of +1.0 EV for its brighter skin tones, it resulted in far too many clipped highlights for our tastes. Bottom line: while dynamic range isn't bad, the Canon T3i struggled a bit with this difficult shot compared to recent state-of-the-art peers.

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
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. The graph at right (click for a larger version) was generated using Imatest's dynamic range analysis for an in-camera Canon Rebel T3i JPEG file with a nominally-exposed density step target (Stouffer 4110). At default camera settings and base ISO, the graph shows 9.95 f-stops of total dynamic range, with 7.31 f-stops at the "High" Quality level. These are decent numbers, though somewhat lower than some recent competitors. Compared to the Canon 60D which uses the same or very similar sensor, the T3i scored slightly lower at the High Quality level (7.31 vs 7.46 f-stops), and also lower in total dynamic range (9.95 vs 10.5 f-stops). Note though that this measurement has a margin of error of about 1/3 f-stop, so differences of less than 0.33 can be ignored.

RAW. The graph at right is from the same Stouffer 4110 stepchart image captured as a RAW (.CR2) file, processed with Adobe Camera Raw using the Auto setting. The Canon T3i's RAW file scored 0.75 f-stop more in total dynamic range (10.7 vs 9.95 f-stops) but the score at the highest quality level increased only 0.32 f-stops from 7.31 to 7.63, which is not much of an improvement and below average these days. Results are similar to those of the Canon 60D at the High Quality level (7.63 vs 7.75 f-stops), though the total dynamic range score was lower like the JPEG, at 10.7 vs 11.9 f-stops. These numbers are below average for an APS-C sensor these days. 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 High Quality threshold. Also, the extreme highlight recovery being performed by ACR here would likely produce color errors in strong highlights of natural subjects.

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. As was the case with its saturation adjustment, the Canon T3i's contrast setting meets both challenges very well.

At its lowest contrast setting, the Canon T3i did an excellent job of preserving highlight detail, maintaining fairly natural-looking skin tones, and holding nice detail in the shadows. Overall, very good results here, especially when the contrast setting is tweaked.

The Canon Rebel T3i's contrast-adjustment control 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.)

Highlight Tone Priority
The Canon EOS Rebel T3i's Highlight Tone Priority (HTP) option did an excellent job of preserving highlight detail, as shown below. (Mouse over the Off and On links to load the corresponding thumbnail, histogram and crops.) 

Both shots above were captured at the same exposure, the only difference being that HTP was enabled for the second shot which necessarily increases the ISO to 200; part of how HTP works. The result is evident in the histograms and crops above, clearly showing the superior highlight preservation when HTP is enabled, while shadow brightness is left relatively untouched. As you can see from the shadow crops, an increase in noise is however the price you pay when ISO is boosted from 100 to 200. (Note that levels were significantly boosted in the shadow crops to reveal the increase in noise.)  Except in the very deepest shadows, though, overall noise is low enough at ISO 200 that this is really a negligible trade-off for all but the most critical applications.

Automatic Lighting Optimization
Like the EOS 60D and Rebel T2i, the Canon Rebel T3i offers three selectable levels of Automatic Lighting Optimization (ALO), plus Off. In fully automatic and Creative Auto exposure modes, ALO is automatically enabled. All four shots below were taken with the same default exposure settings. Mouse over the links below to load the associated thumbnail and histogram, and click on the links to load full resolution images

As you can see above, ALO has the effect of shifting shadows and mid-tones in the histograms to the right, brightening shadows and indeed most of the image without clipping too many additional highlights. ISO is not boosted for ALO so increased noise is not an issue, though it may be slightly more visible in shadows that have been boosted significantly.

Face Detection
Just like most point & shoot cameras these days, the Canon EOS Rebel T3i 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 works well, as the center image with face detection enabled is better exposed for the face (though still slightly dim) than the left image where face detection was not employed. Portrait Scene mode (right) did even better, producing the best overall exposure. Portrait mode also selected a much wider aperture, making the depth of field shallower to help isolate the subject from the background, and the camera also rendered skin softer, presumably to mask imperfections.

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 EOS Rebel T3i 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). As is often the case, the T3i's auto exposure system struggled to produce a good exposure the lowest light levels, so we used manual mode for these shots. As expected, noise increases as ISO goes up and light levels go down, but noise remains fairly low up to ISO 1,600. At ISO 3,200 and above, noise is higher and a few bright pixels appear. Color balance was pretty neutral with Canon Rebel T3i's Auto white balance setting (just a touch cool), even at high ISOs, though at lower light levels white balance became a little warm with a reddish tint. There were a few hot pixels at low ISOs and low light levels with noise reduction turned down, as well as some bright pixels at higher ISOs, but nothing unusual. Some faint horizontal banding can be seen in darker areas at very high ISOs, but that's not unusual either and shouldn't be a problem for properly exposed subjects.

When using the optical viewfinder and phase-detect AF, the Canon Rebel T3i's autofocus system was able to focus on the subject down to below the 1/16 foot-candle light level unassisted with our Sigma f/2.8 lens, and in complete darkness with the AF assist enabled. In Live View mode using contrast-detect AF, the Canon T3i was able to focus down to between the 1/4 and 1/8 foot-candle light level, which is fair.

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 T3i do much better than point & shoots, but you still shouldn't expect a quick autofocus lock with moving subjects.

Print Quality
Excellent print quality from ISO 100 to 400; ISO 3,200 shots still make good 16x24 prints; ISO 12,800 produces good 8x10s.

ISO 100 images are excellent, with sharp detail when printed at 20x30 inches, with good color and no trouble with noise. ISO 200 and 400 shots are essentially identical, with excellent detail across the board.

ISO 800 shots also look good at 20x30, though the slightest softening occurs in very low-contrast areas. Color and detail, though, are good.

ISO 1,600 images start to show some of the noise in shadow areas, and detail begins to soften as well. Yet the print size is still 20x30. Low-contrast reds, especially our red leaf swatch, starts to show the first signs of "creative interpretation" of what the fabric looks like.

ISO 3,200 shots are usable at 20x30, luminance noise is noticeable in the shadows, and the red swatch continues to deteriorate. Even higher-contrast detail softens from the noise suppression, so reduction to 16x20 is warranted, where all these elements improve.

ISO 6,400 images are usable printed at 13x19 inches, though at this setting the red leaf swatch is very soft and would look so even at 4x6 inches. (Many cameras have this problem, so we'll stipulate it from here on.) Better image quality is obtained at 13x19 inches.

ISO 12,800 files print surprisingly well at 8x10, though close inspection reveals dark grain in shadow areas. 11x14-inch images would be usable provided the subject background was dark enough (a setting in which you'd expect a little more noise).

Overall, the Canon EOS T3i does just about as well as its 18-megapixel brothers, and fares very well against the competition. Safely shooting at ISO 800 and still expecting to produce a 20x30-inch print really opens up some possibilities for a photographer. Finding excellent usability at even its highest ISO setting is comforting.

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.)