Hi there.
I’ve used a few different types of compact cameras underwater, including Sony, Canon, and Olympus cameras.
I agree with previous posters that 12Mpx really isn’t necessary unless you want to enlarge your pictures to A3 or bigger. You would probably be better off aiming lower down the Mpx range and saving a few dollars to be spent on other features.
There are a few aspects of compact cameras that I think generates a differential between good for u/w use, and not so good:
- a large, bright LCD screen (although it does need to deliver a quality image - if the screen looks fuzzy and indistinct in the shop, its not going to get any better underwater!)
- being able to access all the controls on your camera whilst it is in the housing. I know some recent sony cameras have settings like macro controlled via a touch screen lcd. Whilst this is great on land, the housings don’t allow you to access any touch screen settings underwater, so you are forced to choose whether you are shooting macro or not before you jump in the water. Very limiting, so in choosing your camera, check that the housing that goes with it allows you to access all controls. Personally I would avoid touch screen controls unless there are limited to playback options only.
- the lens. Of course, the lens is a critical factor for all cameras, but underwater, where light is less abundant than above, the lens can be even more important. Compact cameras by their very size have to sacrifice lens size; by that I mean the physical size of the lens. A larger diameter lens will let in more light than a smaller diameter lens. Some of the compacts (especially Sony) have very small diameter lenses, and I question how good some of those would be underwater. Bear in mind that as the lens diameter increases, the optics of the glass also has to improve, otherwise image quality degrades, irrespective of how much light the lens ‘gathers’.
- wide angle. Underwater, the magnification of the water means that you typically want as wide an angle lens as possible (all other things being equal!). Most compacts have a ‘35mm equivalent’ wide angle of 35mm. This is OK, but if you can get a wider angle lens (28mm is about the best I have seen in any compact), then there is arguably benefit in doing so. Unfortunately, very few compacts offer this. You can however, get wide angle adapters for many underwater housings (additional lenses that attach to the front of the housing), and these can give you really wide angle set ups.
- shutter lag. I note some discussion on shutter speed, which I assume actually refers to shutter lag, which is the delay between pressing the shutter button and the camera actually taking the shot. Current compacts are generally better than older compacts in this area. Underwater, I find that if you pre-focus the camera by ‘half pressing’ the shutter button, and then wait for your scene to be as you want, shutter lag is all but eliminated, and all compacts perform pretty much the same. If you don’t pre-focus, then there is some variability in the performance of different cameras, but i think all of them will still be too slow to catch that fish or turtle or shark as it swims past you!
- battery life. You want your camera to last the length of one dive at the very least, if not two. It’s hard to get comparitive specifications on the different cameras, but there are some general points: some current Canon Powershots use 2 AA batteries, whilst a small number use 4 AAs. Logically, the 4 AA cameras are going to have a better endurance, as in general, the cameras all do the same things with battery power - supply a screen, move the lens for autofocus, power the ‘brain’ of the camera which determines exposure, takes the photo and writes it to the card.
- manual exposure control. From what you have said, I think this may not be too important for you, but if you get the u/w photography bug, I think you might find that you start to augment your point and shoot approach with the desire to fiddle with a few settings. For this reason, I suggest that you look for a camera that at least allows you to adjust the exposure (brighten or darken the picture). Most compacts do this, but there are a few that don’t. Other controls that are very useful underwater are the ability to turn the flash off or force it to be ‘always on’, a macro focus mode, and a manual focus mode.
- white balance. Quite a few compacts have an underwater white balance pre-set, and some allow you to do a manual or custom white balance, which in tandem with your magic filter would be a handy feature to have.
- housing considerations. Many of the compact camera housings from the camera manufactures end up postively bouyant underwater, which I personally find to be quite annoying, because the camera either floats up from the wrist strap, or from a lanyard (I use a lanyard to attach my camera to my BCD), and murphy’s law dictates that the camera will always float around infront of your face when this happens. Thus I prefer a slightly negatively bouyant rig which tidily keeps out of the way when not in use (beware dragging it over the reef though!). Of course you can bolt on small weights to bouyant housings to resolve this, but setting this up is a drag. Canon housings are particularly prone to bouyancy in my experience, Sony less so, and Olympus almost always are negatively bouyant.
Anyway, I hope that at least some of that is helpful.
good luck!
