Posted 16 May 2014 - 03:31 AM
I'm assuming you're dealing with an electronic viewfinder. Are their any viewfinder brightness or contrast or RGB level options you can adjust for night dives? Does the camera support any focus peaking type highlighting options you could set for a different color (white, yellow) so it would show up in contrast to the red ambient view and thus at least help you see the outlines of what's presently focus locked?
I have a sort of similar issue with the Sony SLT-A55. The original SLTs (A-33, A-55) always try to give a what-you-see-is-what-you-get view related to your settings, which means that if the camera doesn't know strobes are present (manual synced, not TTL-connected) the viewfinder helpfully goes "black" with settings like ISO400, f8, 1/160th in dim underwater conditions, although the AF boxes still light up green because the AF module has plenty of light to focus lock. My only solution was to go to a TTL connection or like you are experimenting with provide a butt-ton of focus light. That much focus light of course scares off critters and is still less than a strobe so I'd barely see what I was trying to frame...the TTL is the more usable option for me. (Newer Sony SLTs have a menu option to disable this 'setting effect' on the electronic viewfinder so the view always mimics ambient levels instead of the setting levels.)
Current rig: Sony SLT-alpha55 in Ikelite housing, Sigma 105mm f2.8 DC Macro w/ Ike 5505.58 flat port or Sigma 8-16mm f/4.5-5.6 DC HSM behind UWCamStuff custom 5" mini-dome. Dual INON z240 Type IVs triggered with DS51 for TTL mimicry, or DS51 alone with home-made ringflash assy for macro.
Topside, unhoused: Sony SLT-alpha99,
Sigma 150-500mm + 1.4TC (Saving for Sony 70-400 G2), Sigma 15mm diagonal fish, Sony 24-70mm f2.8 CZ, Tamron 180mm f2.8 Macro...all the gear and nary a clue...