I'm an inexperienced amateur underwater photographer, and I'm interested in buying a new compact camera, my main interest being underwater macro photography (e.g. of nudibranchs). For reasons of budget and of specs, I've narrowed it down to a couple of models: Canon Powershot S120 and Canon Powershot G16, and I was hoping to get some help deciding which one to buy.
The G16 is clearly the better model for my purpose, with a minimum of 1 cm focusing distance (against the 3 cm of the S120). Although it would be hard to get this close to a subject underwater, I seem to understand that a shorter min focusing distance means it is in general easier to get a good macro shot (for example in terms of focus speed).
The S120 is much more versatile, as it is smaller and has touch screen. It is also cheaper, and housings are cheaper.
The type of advice I am looking for is for someone to quantify exactly how much better the G16 is at taking underwater macro shots than the S120. I'm hoping for the gap to be small enough to justify me buying the S120, and I would also consider getting the ikelite housing with the wet-mountable add on macro lens to get the magnification I need. But since macro photography is the main reason I'm buying this camera, if the G16 takes considerably better shots than the S120 (considering, of course, they can be both be upgraded with the above-mentioned lens), I would go with the G16 despite the increased bulk and higher pricetag.
Thank you very much for any advice!