Wow, this looks like a consumer feedback questionaire...
how useful/necessary are the 'my modes' settings for underwater? eg does the fact that the 4040 doesn't have them constitue a major disadvantage?
You can save upto 8 My Mode settings on the 5050 with info like modes (P, M etc.), Macro, Super Macro, Manual focus, shutter speed & aperture (mode allowing), picture quality, flash settings, etc. So it's very powerful - only problem is remembering which mode contains which settings (wish Olympus would have a naming function). You can also program My Mode as a shortcut or into the 'Custom Button' and thus access the modes with the touch of a button. It's a 'nice to have' feature but I wouldn't consider it a major advantage.
how does the new placement of controls in the 5050 change the ease of use compared to previous models?
I haven't used a 4040 extensively but the 5050 controls are very straight forward and easy to use. My biggest quibble underwater is with the aperture control in M mode - holding a button down on the left of the housing and turning the knob. Tough with a large-ish housing, strobe hanging off the end of it, elusive subject and a strong current thrown in for good measure. But you get used to it...
how accessible are the manual controls on the 5050? how does one focus manually?
In M mode the shutter speed is changed by turning the dial and aperture as mentioned above. Manual focus is done by pressing the up and down buttons and an enlarged view is shown in the centre of the viewfinder with the distance scale on the left.
I don't use it much UW but find it very handy topside, especially shooting in macro and super macro. Having said that the AF is generally very good. It also has an AF assist lamp for low light situations. A good tip is to get the camera to give you a close AF then switch to MF and fine tune.
other than pixel size, f stop and depth possibilities of the housings, what points would you feel the most important in deciding for or against one of these configurations and why?
I was about to purchase the C4040 but decided to wait (9 months) for the 5MP version as at that time I was very sure they were going to release one soon. And I'm glad I did.
The biggest factors were the higher pixel count(obviously), newer and faster technology xD picture card (support to 8GB proposed), accepts 4 different types of media in 2 slots, ability to copy from one media slot to the other, Super Macro (3cm), ability to disable pre-flash in A and M mode, larger internal buffer and standard external flash hot shoe. What came as a bonus was the ability to fire the flash in Super Macro mode. Other bonuses - ability to save in RAW format, histogram, improved menu access with the ability to set 6 functions by holding down the direct buttons and turning the jog dial (flash modes; flash intensity; shooting modes macro/super macro/AF/MF; aperture for manual mode which doubles as an exposure compensation in P, A and S modes; metering method and remote/self timer functions), tiltable (topside, up and down only) viewfinder.
To me the higher pixel count now seems to be negated by the high noise ratio even at ISO 64 because it uses the same lens and the same size CCD as the 3040 and 4040. Mind you the fast lens was one of the reasons I bought the Olympus. Having said that I've found noise reducing software that does a brilliant job.
and are replacement o-rings available for the housings?
Yes. The PT015 uses 2 servicable o-rings and having 2 between your camera and disaster is a very comforting feeling.
Opinion: Definitely get the C5050 over it's predecessors. Or, if you're willing to wait, get the C4040 and wait for the next one - pretty sure the next one from Olympus will be a 'next generation' as I think they've pushed the lens and CCD size to the max.
