With most DLSR's you will need to compose through the eye piece. With the Nikon D70 there is no real time display but it does show you the picture immediately after taking it. On the rear of the Ikelite housings there is a built in "magnifying glass" behind the cameras eye piece that helps you to use the cameras eye piece (viewfinder). I would imagine that all housings are like this but I only have experience with the Ikelite housing and Nikon D70. When I first realized this it seemed like a big difficiency but you get used to it and after using the system for a while I don't see it as an issue anymore.
When I moved from the Nikonos to the housed DSLR my pictures got better immediately....even the first time using it. The Nikon DSLR's have a highlights feature where it will display the photo with highlighted areas that are potentially overexposed (I am sure the Cannon's also have an equivalent feature too). This is nice because you can make adjustments and take the shot again if needed. I am not a great photographer... but with digital I just use statistics on my side. I take alot of pictures and with some luck.. a couple will turn out pretty good
