TechReviewSource.com posted a review on the Canon PowerShot G15
The G15 is one of the few point-and-shoot cameras on the market with an optical viewfinder. Nikon dropped the finder from its latest Coolpix P7700, which leaves the G15 standing alone with the Canon PowerShot G1 X and the Fujifilm X10. An optical finder makes it appealing to a certain niche of photographers, but not all viewfinders are created equal. The G15 and G1 X both have zooming finders that are rather small and dim compared to the big, bright one packed into the X10. If you're buying on that feature alone, the X10 is the clear winner.Canon PowerShot G15 Review
At 3 by 4.2 by 1.6 inches (HWD) and 12.4 ounces, the G15 is larger and heavier than a smaller big-sensor camera like the Canon PowerShot S110, which features the same size 1/1.7-inch CMOS image sensor, but omits the optical finder and hot shoe. The S110 is much easier to slide into your pocket at 2.3 by 3.9 by 1.1 inches (HWD) and only 7 ounces.
The 5x zoom lens covers a 28-140mm equivalent field of view, with a variable aperture that starts at f/1.8 at the wide end and drops to a very reasonable f/2.8 on the telephoto side. It's faster on both ends than the G12, which starts at f/2.8 and dwindles to f/4.5 when zoomed in. The Sony RX100, which features a larger 1-inch image sensor, starts at f/1.8 but drops to f/4.9 when zoomed in—that camera does better at very high ISO settings, however, which nullifies the G15's advantage in lens speed.
