Automatic mode is not always available

My son has some shooting problem in the dark bottom of sea diving, as storobo lighting is used in the scenery, it is impossible to know the adequate EV value before shuttering. We should remind back, APEX, the principle of exposure, Additive system of Photographic EXposure. EV=AV+TV and EV=BV+SV, 2 different formulae must be satisfied at the same time. EV:Exposure Value, AV:Aperture Value, BV:Brightness Vale and SV:Sensitivity Value, promptly. Relative value on the right side and absolute value on the left side. Even in the darkness, SONY Alpha camera emphasize the pics on back LCD viewer and the pic obtained should be lighted by strobo light, then the EV differs as a matter of fact. On the other hand my sensitive point is long period time exposure for night shooting, trial and failure repeating would solve my problem. so I hope. The truth will be proved when consistently lasting rainfall stops, it looks like exactly Rainy season, stop it AS. My recent study proved that the problem of Reciprocity foul does not matter in Digital format that had been attacked and did harm while the Silver Salt film period. It's an indispensable gospel for me because I had been suffered from it in close up shooting under the assistance of storobo lighting.