In the last weeks had the first chance to shoot 4k (or more correctly, 3840x2160p24) video underwater, using the new Nauticam NA-LX100 housing with a Panasonic LX100 inside.

If you are interested in the results I could achieve, download this 5 minute sample video I prepared (size: 1.1 GB): https://archive.org/download/na-lx100-sample/na-lx100-sample.mp4

No artificial light, no stands or other accessories were used in its making.

This video was encoded at 32MBit/s in H.264 - somewhat the minimum of what needs to be invested to provide a decent reproduction of the original (100MBit/s) recording. Notice that it won't make sense to upload this sample to "streaming video hosters", as those typically limit the video bandwidth to ridiculously small values, turning "swarms of moving fishes" into mere "displays of mushy compression artefacts".

Please download the complete MP4 file before replaying it locally, it's unlikely that archive.org can provide you with enough bandwidth to replay it "on the fly".

@Vitaliy_Kiselev: I included some shark footage especially for you, so you can see how well behaved they are :-) - even though moving, bigger animals, are almost impossible to get pictures of that would really benefit from 4k resolution.

My findings on the usuability of the LX100/NA-LX100 for the purpose:

Pro:

• great lens for almost all underwater scenarios, including macro shots
• white balancing much better than with the GH2 - color correction in post can be much more gentle
• very good resultion and reasonable recording bandwidth in 3840x2160p24

Neutral:

• focusing still usable only with "AFS" and manual - no reasonable operation with continous autofocus, "depth from defocus" only used for still images

Con:

• optical image stabilization generally useful but does cause annoying "stuttering" for intentional pans.
• Insufficient recording bit rates for 1080p modes - so you can't opt for e.g. 1080p50 shooting if you are after Sailfish, Dolphins or alike were 4k wouldn't reveal more details anyway

BTW: It would really help if Panasonic allowed to assign a "trigger AFS" function to some function key - it is annoying that if you press slightly "too hard" on the trigger to only "half-press" it, some unhelpful error message ("cannot take picture while recording") will pop up when you try to re-focus while recording.