Canon G7 Exposure

Saturation & Hue Accuracy
Slight oversaturation in reds and blues, though good hue accuracy and great color overall.

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. The Canon G7 does oversaturate reds and blues, but overall saturation is quite good. 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. In this case, the Canon G7 did produce just slightly warm skin tones, but many consumers prefer the "healthier" appearance of warmer skin tones. The camera also offers light and dark skin tone enhancement options through the My Colors menu. Red was quite a bit more controlled than we see on most Canon cameras.

The other important part of color rendition is hue accuracy. Hue is "what color" the color is. The Canon G7 typically produced a nearly accurate color balance with the Manual and Auto options, depending on the light source (though results were slightly warm under harsh sunlight). It also pushed cyan toward blue, reds toward orange, and yellows toward green, but overall results were still quite good.

Exposure and White Balance

Indoors, incandescent lighting
Good color with the Manual white balance setting, less positive exposure compensation required than usual.

Color balance indoors under incandescent lighting was a little warm and yellow with the Auto white balance setting, though the Manual and Incandescent options both produced more accurate results. In the end, I chose the Manual setting as the most pleasing overall. The Canon G7 required only a +0.7 EV positive exposure compensation boost, which is less than average. Though maybe a hint warm, overall color with the Manual white balance setting is quite good, though the blue flowers appear quite dark. (Many digital cameras have trouble here.) 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
Bright colors overall, though a slight warm cast and high contrast under harsh lighting. About average exposure accuracy.

Outdoors, the Canon G7 tended toward a slightly warm color balance, though overall color was generally pretty good (if a little on the dark side). The Canon G7 required slightly less positive compensation we're accustomed to seeing among consumer digital cameras under these conditions. The G7's default contrast is high, producing washed-out highlights and dark shadows under the deliberately harsh lighting of our "Sunlit" portrait test shown above left. The camera's contrast setting does a pretty good job of toning down the highlights however, without dimming the exposure too much.

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

Resolution
High resolution, 1,400 ~ 1,600 lines of strong detail.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,600 lines per picture height horizontally, and only to about 1,400 or 1,500 lines vertically. Extinction occurred at around 2,000 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. Beware that while you might be able to make out what looks like distinct lines at numbers higher than those we've mentioned here, the camera is just doing its best to continue interpreting the lines.

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

Sharpness & Detail
Sharp images overall, though slight edge-enhancement on high-contrast subjects. Some noise suppression also visible in the shadows.

The Canon G7 captures sharp images overall, though some slight edge enhancement artifacts are visible on high-contrast subjects such as the crop above left. (Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.)

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. The crop above right shows noise suppression in the darkest areas of Marti's hair, though quite a few individual strands are visible in the lighter shadows. Noise suppression is particularly active in the G7, unusual for a Canon camera, especially at low ISO.

ISO & Noise Performance
Low noise at the normal sensitivity settings with evidence of noise suppression, and a big jump in noise with strong blurring at the highest settings.

Noise levels are quite low at the Canon G7's lower sensitivity settings, with only moderately high noise at the ISO 400 setting. Noise increases dramatically at the 800 and 1,600 settings, with a severe loss of fine detail at ISO 1,600. However, as mentioned above, noise suppression is clearly at work at all ISO settings, quite a disappointment coming from Canon.

Extremes: Sunlit and low light tests
High resolution with strong overall detail, but high contrast. Excellent low-light performance, capable of capturing bright images under average city street lighting and much darker conditions.

Sunlight:
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 Canon G7 produced high contrast with strong highlights and deep shadows under the harsh lighting of the test above. However, shadow detail is pretty good, despite some noise suppression. The camera's low contrast setting did a pretty good job of toning things down without dimming the exposure too much, though the effect is still a little subtle. I preferred it to the image at +0.7 EV, which is slightly less positive exposure compensation than average. (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.)

Low light:
The Canon G7 captured bright images down to the 1/16 foot-candle light level (about 1/16 as bright as average city street lighting at night), at all available ISO settings. The Auto white balance setting produced good color as well. The camera's autofocus system was able to focus on the subject down to just above the 1/8 foot-candle light level unassisted. Do keep in mind, though, that the very long shutter times necessary here absolutely demand the use of a tripod or other camera support to get sharp photos. (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.) For such applications, you may have better luck with a digital SLR camera, but even there, you'll likely need to set the focus manually. For information and reviews on digital SLRs, refer to our SLR review index page.

Coverage and Range
Good flash performance, with good coverage and intensity. Less positive exposure compensation required than average.

Flash coverage was uneven at wide angle, with falloff in the corners of the frame. However, at telephoto, coverage is much more even, with minimal falloff. Indoors, under incandescent background lighting, the Canon G7's flash produced dim results at its default exposure setting, requiring a +0.7 EV positive exposure compensation boost. There's a slight orange color cast to the background from the incandescent light source, but overall color is pretty good. With the camera's Slow Sync flash mode, coverage is more even, though the orange cast is a bit stronger. Despite the longer exposure time, results were best with a +1.0 EV exposure boost.

The Canon G7's flash was bright and powerful, with good intensity all the way to 16 feet at ISO 100.

Our standard test method for flash range uses a fixed setting of ISO 100, to provide a fair basis of comparison between cameras. We've now also begun shooting two shots using the manufacturer-specified camera settings, at the range the company claims for the camera, to assess the validity of the specific claims. In the shots above, the G7 performs as Canon says it will, producing good exposures at the rated distances with its ISO set to Auto.

Print Quality
Good print quality, great color, good 16x20 inch prints. Ultra-high ISO 1,600 and 3,200 images are soft but usable only at 4x6; ISO 800 shots are still good at 8x10.

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 i9900 studio printer, and on the Canon iP5200 here in the office. (See the Canon i9900 review for details on that model.)

With the Canon PowerShot G7, we found that it had enough resolution to make good looking 16x20 inch prints. At high ISO, image noise levels are held in check up to ISO 800, but the jump to ISO 1,600 gets quite a bit rougher. ISO 1,600 shots under daylight-balanced lighting look okay at 5x7 inches, those shot under incandescent lighting are really only usable as 4x6 inch snapshots with high contrast and plugged shadows. ISO 3,200 are about the same.