In my first trip with the GH4 I shot in a open cenote at -35m with the Pana 7-14mm. Some of the takes were shot with MWB done at around -17m (A), and some of them with the MWB done at shooting depth (-35m) (B). All of them at maximum aperture (f/4) and 1/25 (25fps).
I found B colors nicer compared with the greeny A shots but I noticed B shots were much noisier!!. Since my old HC9 was not able to WB under -15m, and I guess on land the electronic adjustments are not extreme enough to notice such a thing, I was very surprised and disappointed with this issue.
In my next trip I'm planning to shoot sharks in deep (-40m) channels in Maldives and I'm definitely going to try red filters in my lenses (Pana 7-14 and pana 12-35) as a work around for white balancing in this situations (red filter plus MWB or AWB. I'll try both).
Which filters would you recommend me. And, most important, how can I put a filter in front of the 7-14mm since it has no thread at all???!!!
Shutter Speed thoughts
I might be wrong, but I have the feeling that if you film at over 180º you are breaking some golden rule (I got this impression after reading a lots of forums and watching video tutorials). 15 years ago it did't happen, I guess it comes when the borderline between video and film are becoming softer and softer.
I wonder why really do we want to shoot with 180º!!!. Ok, the book says you get the "most cinematographic" look. But, besides this, why?.
I mean... we should be adapting the shutter speed to our filming situations. Down there we are always claiming for more light, we die for fast lenses, we hate noisy high ISO. So, what's wrong with going 360º?.
Furthermore underwater everything moves much slower, you probably will get the same motion blur at 360 shooting a Manta swimming as shooting a turtle running on land.