I think that for a budget-concious approach, something like the G9 or G10 is a great camera setup for the price. My wife and I put together a G9 housed setup for her to use when I'm busy shooting something else and the turtle/shark/whatever passes on the other side of the coral head/ship/etc. What's particularly nice about the G9 (I assume G10 as well, but I don't know it's specs) is that you can shoot RAW, and if you can you should.
I think the back up option is go with something like a canon g9 or g10 with external strobe and case which is a ton cheaper and easy to buy used and then I could keep or easy to sell as well. I would like to stay on canon as I am most familiar with it.
Second, if I decide not to spend that much I was thinking about a canon g9 or g10 with the simple case and a strobe flash (I assume you can get an external flash that is either ttl or slaves off of the built in?). I know the photos will not be as good, but I think they would be *good enough*. Yes I know all depends what is good enough.
I know we got a Canon housing and YS-27 strobe for around $450 total (via E-bay), and we already had the G9.
If you'd like some samples, they're easy to find online, but I can certainly send you some shots from inside the SC Aquarium that my wife took on the first housing test dive. She hasn't shot underwater since our advanced training 7 years ago, so they'd be a sample of shooting in dark conditions with an inexperienced user. Just PM me an address to email them.
IIRC, some strobes do, for instance DS-TTL "digital slave" strobes like the YS-110 that can do TTL using the optical cable.
1. For the external strobes do they trigger on ttl (does that mean the camera triggers them when you take a photo) or do they trigger like slave off of the built in flash? Or you posted that they fire optically...is that different still?
However, there's the debate over whether TTL is really necessary:
the sample pics I've offered to send you were shot using the manual strobe adjustment approach.
One of the advantages to shooting in RAW is the ability to easily adjust white balance post-dive. That being said, I tend to deal with white balance more on an ambient light photo than one lit by strobes, as strobe color temperatures are much closer to daylight that the cool blue of open ocean.
3. Do I really need to white balance? Can't I just shoot with the flashes and won't that mean I don't have to white balance? Should I just set on cloudy?
As I said before, we got the canon housing for the G9 and a YS-27. The Canon housing is a bit cheaper than the ikelite, iirc. Here's the costs we paid (incl shipping) and setup:
5. Lastly...what do you recommend for a G9 rig- what case and what flash (do I need two)...that is reasonably priced? I'll probably buy it all on ebay...
Canon WP-DC21: $155 (Ebay)
Sea&Sea YS-27(w/ optical cable): $270 (Ebay)
Plate for strobe arm: $12.99 (Ebay)
Sea & Stay IV: $17ish (Subaquatic Camera)
Of course, you might be able to do better than these prices by spending more time hunting than we did.