LCD AND VIEWFINDER
Both Canon S110 and G15 have a 3 inch fixed LCD, but the one on G15 has higher dot count (922,000 vs. 461,000 on S110). I could not spot major display quality difference in real life use, but enjoyed very much in a touch-sensitive display on Canon S110. The ability to focus and take a shot with just a light touch on LCD is a very strong argument toward S110, especially considering the camera’s small size and small number of external controls.
G15 on the other hand has a viewfinder. It’s an “optical tunnel” type of viewfinder with its own zoom mechanism to emulate lens zoom position. This type of viewfinder was almost obligatory in compact cameras around 10 years ago but disappeared quite fast when LCD sizes jumped above 2.5 inch. The one used on G15 is small by today’s standards yet it can be a very important feature in many situations. It makes possible to frame a shot in very bright sunlight when LCD becomes too dim for normal use, and can extend battery life almost double of what’s available in live-view mode (you need to turn live -view off manually).
CANON G15 VS S110 SENSOR AND HIGH ISO PERFORMANCE
Both cameras use the same sensor – a 1/1.7″ CMOS unit with 12 megapixels and native 4:3 ratio. Image quality is excellent at lower ISO settings. Very soon it becomes clear that G15 and S110 have distinctively higher image quality than other Powershot cameras. The ability to retain details at 100% viewing without introducing JPEG compression or noise reductions artifacts is astonishing. When used in RAW mode, both cameras show what they’re really capable for. Colors are a bit bleak at default settings, but that’s expected from a cameras aimed at advanced users – it provides more space for manipulation.
As far as higher ISO values are concerned, I didn’t hesitate to use both G15 and S110 up to ISO 800. ISO 1600 still looks rather good for such a small sensor, but 3200 and higher can be a bit of a stretch; with good exposure and post processing you can get usable results but is maybe best avoided if image quality is you main concern.
There is an irritating bug/feature though: every time I selected shutter speed longer than 1 second both G15 and S110 would set ISO at 80 and there is no way around it. I couldn’t figure out thelogic behind this feature, but it limits low light usage for both cameras. Nikon P7700 and Olympus XZ-2 I tested last year didn’t have such limitations.
Both cameras produce very pleasing JPEG’s at Auto mode and I rarely needed to use EV compensation to get enough brightness in photos (unlike recently tested EOS M). G15 and S110 may be cameras aimed at more demanding users, but they kept amateur-biased image processing engine and that’s very good.
MEMORY AND BATTERY
Both cameras use Li-Ion batteries. S110 can take around 200 shots on a single charge, and G15 gives more, around 250 or 300 in my experience. Using only optical viewfinder this can be almost doubled to around 600 shots what is really excellent for a compact camera.
Canon S110 and G15 cameras use standard SDHC memory cards for recording videos and photos.
Both cameras still have a long known bug that plagues Canon cameras… they shut down when you open battery/memory card compartment door. If the door brakes, camera becomes unusable.
CANON G15 VS S110 LENSES
Both cameras have 5x optical zoom lenses but not the same focal length. Powershot S110 has wider wide angle – it starts at 24mm equivalent and goes up to 120mm. G15 on the other hand starts at a bit narrower 28mm, but can zoom up to 140mm. You’ll have to decide by yourself what’s more important to you.
Below; S110 at 24mm left, G15 at 28mm right:
Below; S110 at 120mm left, G15 at 140mm right:
A clear advantage is seen when comparing widest apertures. S110 has F/2-5.9 aperture… Nice and bright at wide angle but a very dim F/5.9 at maximum zoom limits usability in lower light conditions. G15 is much more generous – F/1.8-2.8 brings water to my mouth. That’s a third of a stop brighter on wide angle, and more than two full stops on maximum zoom.
Both cameras have a “step zoom” feature which allows zooming in fixed steps preset at popular focal lengths (24/28, 35, 50, 85, 105 and 120/140 mm).
In terms of optical quality, both lenses are very similar in sharpness. G15 has an edge in terms of bokeh; F/2.8 aperture at 140mm renders more pleasing out of focus areas than f/5.9 at S110′s 120mm (example on the left).
S110 and G15 have built-in ND filters similar to other competitors like Nikon P7700 and Olympus XZ-2. The filter reduces light by 3 EV stops and is intended to be used for long exposure in bright light or the ability to use maximum aperture to allow shallower DOF.