Correction to my previous post...
NZcaver wrote:When the time came to get a new compact digital recently, I looked at the current Olympus models and came away disappointed. I researched several different brands, and even tested and returned a couple of models. I finally settled on a Canon A540, which I'm very impressed with. It has a fast startup time, a short shutter lag, and even manual aperture and shutter settings. However it's not my first choice for a caving camera, mainly due to the old flash/slave synchro issue mentioned earlier in this thread.
Actually I
can set my Canon A540 to single flash, so it
will fire a regular slave unit.
There's a good chance this might work with some of the other Canon models too. All I did was set the mode to manual exposure, selected my shutter speed and f-stop, and turned the flash on. The camera even gave me the option to set the flash for 1/3, 2/3, or full power. I set up one of my slave flashes, hit the shutter, and bingo - success! I tried all the other modes (auto, aperture priority, shutter priority, nightime mode, etc) but manual exposure is the only one that gives a true single flash. Guess I should really read the camera manual one of these days.
Since I was on a roll, I also tested the depth of field on the A540. Zoomed in all the way (23mm - aka 4 times zoom) the widest f-stop I can select is 5.5, and the smallest is f8. My test frame included subjects from about 0.3m to 5m away, and the result was a slight but noticeable difference in DOF. Zooming out all the way (6mm), I then compared shots at f8 and f2.6 (widest aperture) in the same room. The difference in DOF was again quite noticeable, but doesn't give the same control I get with my larger C-5050 Zoom or an SLR.
Conclusion - the little A540 does have some form of aperture that affects depth of field. I'd post the photographic evidence, but the test shots aren't very interesting - they were taken above ground. Oh and FYI, Canon make a waterproof housing for this camera too. Another item to put on the wish list...