Hi,
Firstly, great forum - I've scrounged through a lot of pages and am correcting the error of my ways 
Basically I'm new to underwater photography even though I have been involved in commercial photography for a good while now and also teach scuba (in between looking after the kids) In the last week I purchased the following items to achieve one of my long term dreams to take underwater photos :
Ikelite iTTL housing for D70s
Ikelite port 5503.50 (recommended for Sigma lens)
Ikelite DS-125 strobe and arm package
to work with :
Nikon D70s
Sigma 10-20mm AF lens
So far I've been impressed with the quality of the kit and eagerly jumped in the pool the other night to give it a go (test watertightness, buoyancy etc) The pictures underwater though did not appear as I expected in that they were all out of focus. To this end I added a +4 diopter close-up to the lens and the piccies look a lot sharper now, but this opened a new thought stream that I hope someone could guide me on ?
Firstly, the Ikelite site states that you do not need a diopter correction for this lens (which is why I didn't get one to start with)
Secondly, I'm not sure whether +4 is overkill or whether a +2 would suffice
Thirdly, it would be cool to do those split water shots but I'm not sure as to what effect having the diopter filter attached will have on the piccies in general
and last (for now), I notice that using the iTTL mode on the flash tends to overexpose the subject to the extent that i need to dial in a -1 EV adjustment - anyone else encountered this or have any suggestions (both with diffuser and without) ?
Thanks in advance for any suggestions or tips
Rgds
NickT
