Canon 40D Image Quality

Saturation & Hue Accuracy
Very good color and hue accuracy overall, though a tendency toward brighter reds and darker blues.

Saturation. The Canon EOS 40D does oversaturate color a little, particularly bright reds and dark blues, but the vibrant color will most likely be very appealing to many users. This approximates what we used to call "Canon color," but Canon has changed how most of their cameras see color since then. See our section on Picture Styles for more on the various color options available with the Canon 40D. 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. Here, the 40D also did quite well, producing natural-looking skin tones. 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 40D did push cyan toward blue, and red toward orange a bit, but overall accuracy was still very good. (The blue to cyan 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.) The other important part of color rendition is hue accuracy. Hue is "what color" the color is.

Saturation Adjustment
The Canon 40D lets you adjust the image saturation, contrast, and sharpness for each Picture Style, via a sub-menu off the Picture Style item in the main Record menu. A total of 9 settings are available, four above and four below the default. This covers a pretty wide range of saturation levels, really about as wide as you'd normally need for normal photography, apart from special effects that you'd probably be doing in software anyway. The fine steps between settings mean you can program the camera to just the level of saturation you prefer.

Exposure and White Balance

Indoors, incandescent lighting

Warm casts with Auto and Incandescent white balance settings, but good results from the Manual and 2,700 Kelvin settings. Slightly above average positive exposure compensation required.

The Canon 40D's Auto white balance setting resulted in a very strong warm color cast indoors under incandescent lighting, and the Incandescent setting produced a warm cast as well. (The Incandescent white balance setting on pro-oriented SLRs is usually set to a color temperature of 3,200K, matching professional studio lighting.) The Manual white balance produced the most pleasing overall color, though the 2,700 Kelvin setting wasn't too far off the mark either. The camera required a +1.0 EV exposure compensation boost for a bright exposure (average or slightly above average for this shot) with all white balance settings. Overall color looks good, though the blue flowers look quite purplish, probably due to the 40D's tendency to punch up the reds in Standard Picture Style mode. (Many digital cameras reproduce these flowers with a dark, purplish tint, so the 40D's performance wasn't unusual.) 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
Good color and exposure, though slightly high default contrast. Excellent preservation of highlight detail though, and Highlight Tone Priority does a superior job of holding onto highlights.

Outdoors, the Canon EOS 40D performed pretty well, with good color and only slight overexposure in the outdoor far-field house shot. The Canon 40D required less than the average amount of positive exposure compensation on the "sunlit" portrait test. Default contrast is on the high side, but fortunately, there's a very effective contrast adjustment to help compensate. At its lowest contrast setting, the 40D did an excellent job of preserving highlight detail and natural-looking skin tones, but did slightly increase the warmth of the color balance. Overall, very good results here, especially when the contrast setting is tweaked.

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

Resolution
High resolution, 1,500 ~ 1,700 lines of strong detail.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,700 lines per picture height horizontally and 1,500 vertically, with extinction occurring somewhere past 2,000. 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
Sharp images with excellent detail definition.

Sharpness. The Canon EOS 40D captures sharp images with excellent detail. Some very minor edge enhancement artifacts are visible on high-contrast subjects such as the crop above left, but results are very good. 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 very little softening due to noise suppression at ISO 100. 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.

JPEG vs RAW

Mouse over the links to compare the difference in sharpness and detail from camera JPEG versus RAW file processed with Canon Digital Photo Profession and Adobe Camera Raw. Camera JPEG settings were Standard, which is the Canon 40D's default setting. We used the latest version of Canon's Digital Photo Professional (DPP) 3.1.0.5, with the sharpening set to level 3. DPP gave the better result overall.

Here we compare sharpness and detail of RAW files from competing models, all processed using Adobe Camera Raw. Note that the Sony A700 is a 12 megapixel camera, so the image appears larger and should technically appear sharper.

ISO & Noise Performance
Low to moderate noise below ISO 1,600, but high levels at 3,200 equivalent.

The Canon 40D produced very low noise levels at low ISO settings, with very little loss of fine detail in areas of subtle contrast (where anti-noise processing takes its toll). Images stayed pretty clean as high as ISO 800, but with a progressive and noticeable loss of subtle detail as the ISO increased from there. At ISO 1,600, we start to see some blotchiness in the shadows, but detail is still quite good. At ISO 3,200 the grain pattern and chroma noise become more prominent, especially in the darker areas. All that said, the Canon 40D's high-ISO noise performance is really excellent; it does an excellent job of making the tradeoff between suppressing noise and preserving subject detail. See the Output Quality section below for more on how these results look when printed.

Noise Reduction vs Detail: Camera JPEGs vs RAW files
To our eyes, the Canon 40D does a better job of making the tradeoff between image noise and subject detail than most SLRs, but let your own eyes be the judge. The crops below show examples of image detail at ISO 3200 from the camera directly, from a RAW file via Bibble, using Bibble's built-in Noise Ninja function (settings of 20 and 0.8 for amount and level), and from Bibble with no noise reduction or other processing enabled.

As you can see from the crop furthest to the right, the Canon D40 makes surprisingly clean RAW files even at ISO 3200. The in-camera JPEGs (the crop at left above) do give up some subject detail in exchange for lower noise, but not nearly as much as some cameras we've seen. With a good noise-reduction program, you can achieve very good-looking images at ISO 3200, with surprisingly little evidence of noise or loss of detail. The left-center above used the Noise Ninja function built into Bibble to reduce noise while holding onto as much image detail as possible. (The full Noise Ninja application could probably do an even better job: The free version built into Bibble offers only basic capabilities: Full capabilities can be unlocked by entering a valid Noise Ninja license code.) The 40D does have an option for disabling high-ISO noise reduction in its JPEG files, the results of which are show in the right-center image above. There's clearly more subject detail and less noise present than in the default camera JPEG, but when you compare it to a RAW export from Bibble with all noise processing disabled (as seen at far right above), it's clear that the camera always does at least some noise-reduction processing.

Extremes: Sunlit and low light tests
High resolution with good overall detail, but slightly high default contrast. Excellent low-light performance.

Sunlight. The Canon EOS 40D performed pretty well under the deliberately harsh lighting of this test, though contrast was a little high at its default setting. As mentioned previously however, the camera's contrast adjustment did a better than average job of handling the harsh lighting. Though the shirt is nearly blown at +0.7 EV at default contrast, I preferred it to the image at the +0.3 EV exposure, whose skin tones were under exposed. Depending on the photographer, you could lean one way or the other, for those 40D owners are going to want to just print an image, and the +0.7 image will produce a better print with little or no tweaking, for pros and fine art folks the +0.3 version retains more highlight detail.

As can be seen from the second set of images, Highlight Tone Priority mode was able to hold onto significantly more highlight and shadow detail, but limits the ISO to 200-1,600; and, like the reduced contrast setting, HTP mode resulted in a very slightly warmer overall tone. (In "real life" though, be sure to use fill flash in situations like the one shown above; it's better to shoot in the shade when possible.)

Note: 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.)

The series of shots above show the results of the different contrast settings. While you can see the extremes, it's pretty hard to evaluate small differences in contrast on tiny thumbnails like these, click on any thumbnail to go to the full-size image.

The crops above show how well the Canon 40D holds onto highlight detail with its default settings, and how much it improves with both the low contrast adjustment and the Highlight Tone Priority (HTP) option. In these shots, the 40D did a better than average job of holding highlight detail, using just its default settings. Dropping the contrast adjustment to its lowest setting produced a significantly better result though. Even with the low contrast setting though, some of the strongest highlights blew out. With Highlight Tone Priority though, full highlight detail was retained, even with the contrast adjustment set back to its normal level. Very impressive: HTP should be a godsend to wedding photographers in particular, where maintaining detail in white wedding dresses is critical.

Low light. The Canon 40D performed well in our low light test, capturing reasonably bright images down to the lowest light level we test at, at all ISO settings. This equates to about 1/16 the brightness of average city street lighting at night, so the 40D should be able to take well-exposed photos in any environment you can see well enough to walk around in. Overall noise was really quite low to begin with, and the camera's Long Exposure Noise Reduction option reduced chroma noise to even lower levels at higher ISOs. The camera's autofocus system was able to focus on the subject down to just below the 1/16 foot-candle light level unassisted, in line with its exposure system, but was not always accurate at the lowest levels, according to Luke, our senior lab technician. (The 40D does have an autofocus-assist light option, but it uses the camera's flash tube as the illuminator, and so requires the flash system to be engaged for it to work.)

A minor image-quality strike at high ISO and long exposures: The ISO 1,600 and 3,200 shots here show some evidence of horizontal banding in the dark areas at the lowest light levels. The crop at right shows the extent of this at ISO 3,200 with an 0.6 second exposure. The effect is subtle but visible, particularly when looking at the full image 1:1 onscreen. At ISO 1,600, the effect is less pronounced, but still detectable. Not what we'd call a serious problem, but it could be an issue for some users in critical applications, so we thought it important to call attention to.

How bright is a foot-candle? 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 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.) For such applications, you may have better luck with a digital SLR camera like the Canon 40D, but even there, you'll likely need to set the focus manually.

Print Quality
Excellent print quality at 13x19 inches, a little softer at 16x20. Up to ISO 800 are still great at 13x19 inches, and ISO 1,600 looks good at 8x10.

The Canon EOS 40D had enough resolution to make decent 13x19 inch prints, if a little soft on close inspection at the camera's defaults. Slight softness is standard from Canon digital SLRs at this level, as the company believes most photographers will prefer to sharpen after capture. Just a little unsharp mask makes 13x19 prints and even 16x20 prints look very good for wall display. RAW images are quite a bit sharper.

Indoor shots. Our most astonishing discovery after printing the Canon 40D's images is that quality is quite uniform up to ISO 800 at 13x19 inches, with the four settings almost indistinguishable from each other. Quality does drop off at 1,600, but these images are still excellent at 11x14. The step to ISO 3,200 makes a big difference, however, with its heavy chroma noise appearing evident at 11x14 and 8x10, not becoming negligible until 5x7. Shots at all of these ISO levels respond very well to post processing in programs like Photoshop and Bibble, making even ISO 3,200 quite useful for both indoor or outdoor shooting.

Daylight Still Life. All of the above is judged based on our tougher Indoor test, where noise in the blue channel usually makes matters harder for digital camera sensors. Our Daylight balanced test is quite a bit better, which is saying something. Here, ISO 1,600 shots were slightly soft but quite usable at 13x19 inches, and ISO 3,200 was surprisingly good at 11x14, with far less chroma noise than we saw in the Indoor shots. You're more likely to use ISO 3,200 indoors, of course, where lighting is more likely to be incandescent or fluorescent, so keep that in mind.

Color does decay just slightly at 1,600 and 3,200, but not as dramatically as we're used to seeing.

Where the rubber meets the road, as usual, the Canon 40D has what it takes to deliver excellent photographs.

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 Pro 9000, and on the Canon iP5200 here in the office. (See the Canon PIXMA Pro 9000 review for details on that model.)