Canon PowerShot G9

Aperture Range [f] 2.8-4.8 to 8 Max Resolution 4000 x 3000 (12M px)
Dimensions 106 x 72 x 43 mm (4.2 x 2.8 x 1.7 in.) Other Resolutions 3264 x 2448, 2592 x 1944, 1600 x 1200, 640 x 480
Weight 370 g (13.1 oz) Sensor Size, Pixel Density 7.6 x 5.7 mm, 28 Mpx/cm2

The analysis has been only performed at the highest resolution setting (12M pixels, RAW mode), and an older type of charts were used. The image quality on a camera's chip depends on the distance from the center of an image, as shown below, with the average resolution in hundreds of line widths per picture height (LW/PH) given below each chart. The "Middle" circle chart is about 1000 pixels from the center (mid point to the side).

lens quality test

The sharpest images are produced at near wide-open apertures. In the picture center this camera delivers maximum theoretical resolution for this sensor, 3,000 LH/PH with a 3:4 picture format (compared to a 2:3 format of SLRs, you'd need to trim some pixels from the bottom & top to yield only 2667 pixels, so you'd get the 2:3 format). The wide angle picture quality, at 35 mm equivalent (7.4 mm), in the corners is much left to be desired reaching two thirds of the resolution in the center. None of the tested SLR lenses, even off brand, performed this poorly at comparable focal length. Better performance is at the 44.4 mm - a tele lens setting - equivalent of 210 mm. The center almost reaches the theoretical resolution limit of 30 LH/PH and the sides are not much worse. Due to a small sensor side the picture quality is worst at the minimum aperture of f/8.0.

Other lens properties. Vignetting is not a problem, even at the maximum apertures. Chromatic aberration is small except at the corners of the wide angle setting. Lens distortions, even at the wide angle settings, are small. The size of the circles at the corners are about the same as that in the center, except that there is a 3.5% elongation of the circles (the ratio of extreme radii of the ellipse) in the corners.

This is a high end of point and shoot camera. It's true resolution matches specifications (3000 lines per picture height) near the image center at the wide angle settings. The tele-setting optical quality is good but not excellent. The shutter lag time is short enough not to cause any frustrations.

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