Can you manually focus the lense with these housings? I bought a fuji e900 in 2005 to get into photography while diving. I have improved my photo technique a lot, and I am now considering upgrading to a slr housing. I've never dived with a such a large camera. I am able to comfortably maneuver with my current equipment, and im reluctant to switch to gear which encumbers my movement. Maybe its wise to rent one for a few dives to see if it is practical for me.