This review was published on August 13, 2007. Since then, this product may have been discontinued or replaced. Pricing and availability may differ from what is stated in the review.
Testing / Performance
Canon digital cameras have typically tested well in terms of color. The SD750 comes with a relatively new Digic III image processor and a relatively old Canon lens seen on other PowerShot models. To see how well the SD750’s combination of elements can produce realistic colors, we photographed the ever-colorful GretagMacbeth color chart. This chart displays colors from throughout the spectrum. We take the SD750’s photographs of the chart and upload them to Imatest imaging software, which compares the original chart’s colors to those from the camera. Below is a chart showing the original colors in the vertical rectangle of each tile, the Canon SD750’s colors in the outer square of each tile, and the SD750’s luminance-corrected colors in the inner squares.
Some of the colors are hard to distinguish from each other, while others are obviously off. Below is another comparison chart to show just how far each color is from where it should be. The Canon PowerShot SD750’s colors are shown as circles, and the ideal colors are squares.
The white appears to be just slightly off-center, but that doesn’t seem to affect the overall color production too much. Most of the colors are tightly tethered to where they ought to be. The most erroneous is blue No. 18, but even it isn’t that bad. Overall, the Canon PowerShot SD750 performed wonderfully with its mean color error at a low 5.34. Colors were nicely saturated at 102.8 percent. The SD750 earned an overall score of 11.24.
The Canon PowerShot SD750’s Automatic white balance setting isn’t as reliable as the presets. It’s most accurate in fluorescent lighting, but the preset still prevails.
The preset white balance settings performed very well. The Auto setting was decent but the presets were always a little bit better. The best performances came from the fluorescent and tungsten presets, as their results were nearly perfect.
The Canon PowerShot SD750 packs a 7.1-megapixel image sensor under the hood. At its top JPEG resolution, we snapped several pictures of an industry standard resolution chart to see how effective it is at capturing detail. The chart is shown below.
[Click to view high-resolution image](http://www.digitalcamerainfo.com/viewer.php?picture=SD750-Res-lg.jpg)
We photographed the chart testing out different focal lengths and apertures to get the absolute sharpest shot, and our best result came from an image shot at f/4.9 and 17.4mm. Imatest screened the image and output quantitative resolution results in terms of line widths per picture height (lw/ph). This unit describes how many alternating black and white lines could fit across the SD750’s frame. On the horizontal edge of the frame, the camera resolved 1714 lw/ph with 9 percent oversharpening. On the vertical plane, it measured 1832 lw/ph with 11.4 percent undersharpening.
These results are on-par with other Canon digital cameras. The Canon PowerShot A620, which also has 7.1 megapixels, resolved 1708 lw/ph horizontally and 1787 lw/ph vertically. The Canon PowerShot SD40 resolved 2013 lw/ph horizontally and 1655 lw/ph vertically. It came out with a very respectable 5.86 overall resolution score that is typical of the PowerShot cameras and much better than the average 7.1-megapixel compact digital camera.
*The range of bright and dark shades that can be recorded in a single image is called dynamic range. A camera’s dynamic range is important when photographing subjects with lots of contrast such as the ocean on a sunny day. A cheap camera with poor dynamic range would blow out the sky as pure white, make the ocean appear pure black, and create an image lacking detail.
To test the dynamic range of the Canon PowerShot SD750, we photographed a standardized chart that shows a series of rectangles ranging from very bright to very dark. Using Imatest imaging software, we determined how many steps the camera could depict at different sensitivity settings. While this test is designed to get the most dynamic range possible out of the camera, it probably won’t perform this well outside a studio. This info is useful for comparing different digital cameras on this site, though.
Below is a chart showing the manual ISO settings on the horizontal axis and the number of exposure values captured on the vertical axis.
This chart seems to correspond well with the ISO chart. The ISO 80-200 settings perform well before making a series of drops. These results are unfortunately typical of compact PowerShot digital cameras. The A640 came out a little better with an overall mark of 6.25. The A620 had a 5.5 score. And the Canon PowerShot SD750 has a similar overall score of 5.53.
All of our other tests are done in optimal studio lighting. Because not everyone shoots under perfect lighting, we dimmed our lights for a few tests. The first test was done at 60 lux, which is equivalent to the amount of light in a softly lit living room after dusk. Our second test is done at 30 lux, which is about the light emitted from a 40-watt bulb. The 15 and 5 lux test are extremely dark and are meant to push the image sensor to its limit.
The Canon PowerShot SD750’s images are quite noisy but still very much illuminated, even in the dimmest of lighting. Some other cameras can do this at the expense of color saturation or quality, but the SD750 held colors nicely in low light. Even at the darkest 5 lux, the mean color error was only 7.14, which is a respectable mark for most models.
When the camera selected slower shutter speeds, the noise level increased, as is normal. A chart is shown below with the exposure length on the horizontal axis and the percentage of noise on the vertical axis.
The amount of noise showed no significant increase, so we suspect some in-camera noise reduction kicking in. Canon publishes that its noise reduction system automatically functions with shutter speeds of 1.3-15 seconds. The SD750’s noise actually decreases between five and 10 seconds before climbing again at 15 seconds.
Overall, the images were a bit noisy, but the camera’s low light performance is still quite impressive.
**Noise – Auto ISO***(1.97)*
We tested the noise produced in the Automatic ISO setting in our brightly lit studio. Most digital cameras choose the lowest ISO setting, and therefore produce little noise. The Canon SD750 chose the ISO 200 setting. The SD750 produced a lot of noise through its ISO range. Thus, it came out with a horrible 1.97 score.
**Noise – Manual ISO***(4.42)*
We tested the noise levels at each manual ISO setting under bright studio lights. The SD50 has plenty of ISO options thanks to the new Digic III processor. Its range extends from ISO 80-1600. Below is a chart showing the percentage of the image degraded to noise (on the vertical axis) in each manual ISO setting (on the horizontal axis).
The Canon PowerShot SD750 produces more noise than it should at the lower ISO settings – and it only builds from there. The results are manageable until about ISO 200 because the amount of noise stays under 1.5 percent of the total image. Beyond that, the noise increases dramatically with each boost of the ISO. From ISO 200 to 400 there's a large increase in the amount of noise. The ISO 1600 setting is hardly usable with 4.5 percent of the image lost to noise; this looks like a jumble of purple and green speckles on subjects. The SD750’s overall score for this test came to a disappointing 4.42.
*Startup to First Shot (8.5)*
The Canon SD750 took 1.5 seconds to start up and take its first shot. This isn’t nearly as speedy as a DSLR, but really isn’t bad for a compact digital camera.
In Burst mode, the SD750 can take shots every 0.6 seconds until the memory card is full. This isn’t incredibly fast by any standard, but the camera’s ability to snap away until the memory is filled is quite impressive.
The SD750’s auto focus system can be sluggish if unprepared. Unexpected moments might flutter by, as the camera takes about a half-second when it isn’t prefocused. When the exposure is locked and the finger is pushing the shutter release button halfway down ’s hard to measure any shutter lag at all.
The Digic III image processor doesn’t need a lot of time to think. It takes about 0.7 seconds to process a shot, which isn’t bad at all.
Bright Indoor Light (3000 lux) (4.76)*
We tested the SD750 under the same bright lighting as we do the still image tests. This time we used the Movie mode and recorded a clip of an industry standard video test chart. While colors and saturation were nearly perfect for still images, video was awful. The mean color error came out to 24.3 and the saturation jumped to 137.7 percent. It really does look like a total opposite to still images. Even the still images’ most inaccurate color, blue No. 18, is one of the most correct colors in video. The noise remained fairly low at 0.425 percent.
The camera turned another flip when the lights were dimmed to 30 lux. The bright lights oversaturated the image but the dim lights caused the colors to undersaturate (see the circles in the color chart below heaving toward the center of the image). Saturation was only 45.9 percent; this is one of the worst we’ve seen. The mean color error remained out of whack at 20.8, and the average amount of noise jumped to 2.61 percent of the video.
We tested the SD750’s top video resolution at 1700 lux and ran the clip through Imatest. The program analyzed it and determined that the camera resolved 252 lw/ph horizontally with 19.6 percent undersharpening. Vertically, it resolved 366 lw/ph vertically with 9.7 percent oversharpening. These results aren’t very impressive, but there aren’t many compact digital cameras that are.
*We went outside the lab for a breath of fresh air and a last bit of testing. We recorded videos of cars driving by and people walking on the street outside our office. The contrast and motion looked good except for some jerkiness when subjects moved out of the frame. The biggest problems outdoors involved metering, moiré, and bleeding of overexposed areas. Subjects moving quickly across the frame caused the metering to flicker.
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