Finally got out and dived this weekend with the BMPCC4K.
Was mainly shooting ambient lighting in 8-25m of water with no filters or lights. I got a couple of shots with lights, but haven't look at these yet.
So fair I was impressed with the housing handling (button layout probably not as good as the GH5 housing if I'm honest - would be nice to have the AF button on a thumb lever, more than a push button on the rear) but button layout is good enough. I purchased the hand strap, but this is not good combo, as you need to move your hand to reach the front dial to change aperture, so took it off as it got in the way.
Screen, in shallow waters, it was hard to see, the focus assist (when you could see it) was very clear, and I found, once I had focused it initially at the beginning of the dive, I didn't need to touch it again. Getting a bit deeper, the screen was lovely, with a clean layout and no lag. Looking forward to adding the 7" atop for better ergo with a deep hood.
Buoyancy needs work, as I was a bit negative and front heavy, but as I found in the pool with the inferno it should balance out nicely.
Really impressed with the highlight handling, close to the surface it didn't blowout the surface like my GH4 and GH5 would have. Colour handling very similar to the GH5, obviously it can't restore what isn't there, but no banding or compression issues either when playing with the colour wheels and channel mixer in Resolve.
Q0 at 60p 4K DCI was no problem with the Samsung T5 drives, no dropped frames or issues. The HFR button is a real nice feature, you tell the camera you want to film in 30p and the HFR button will switch to 30p/60p - but on import to Resolve, it will automatically mark the 60p clips for slowdown. Nice.
A few clips I had a quick look at and play with last night. Need to spend more time with Resolve (as I'm used to FCPX) but happy with the results so far.
Will post up some straight from camera BRAW files later today / tomorrow for anyone interested. (They are huge mind..)
One BIG issue which has reared its head, is due to the camera not doing any in-camera lens corrections (one of the reasons I wanted the BMPCC4k) - the side petals of the WWL-1 are visible in shot shots (I presume due to the OIS in the lens moving) so a slight crop-in (in-post) is needed. I haven't tried it with the OIS turned off - but something to consider.
Overall, from my initial dive, I'm super pleased with the camera and what Nauticam have done with the housing.