I have used several DSLR type systems for video work, including 7D, 5D & GH4 and my biggest issue was always that I was never 100% confident that my footage was in focus and when someone is paying you to get the shot and you are always thinking in the back of your mind, I hope that is in focus, well it is not a good feeling.
I'm certainly not going to bash DSLR users as there are many members here that are getting great results from them.
For me though, having distance markers on the screen means I can lock my focus at 0.3 at full wide zoom and I know 100% of the time that the shot is in focus.
The other features I like of a video system are the ND filters, which I couldn't live without now, a zoom lens, the ability to manually focus and swap between manual and auto focus when needed, focus peaking (which I use mainly for macro work and like ND filters, peaking is a godsend for macro work), the ease of getting into the WB menu and having one push WB and decent auto focus.
The things I like specifically about the AX100 would be the image quality first and foremost, the larger sensor means I can finally pull focus underwater and help to separate subjects from backgrounds, the XAVC-s codec is fantastic for post work and the Gates Housing is well balanced, the main functions are well placed for easy access and the extra items like the top handle and tripod make it a great system to use.
I can't see myself going back to an SLR style setup to shoot video permanently.
The GH4 was a great camera and I see people adding all sorts of extra equipment onto it to make it "better" but the size is growing and so is the cost.
Price up the cost of an SLR system versus a video based system, in most cases it is cheaper to setup a video system and I certainly understand that not everybody wants to be locked into a video system and that is fine but for me, it is a dedicated video system all the way.
Whether that be Sony, Canon or whoever else comes along in the future.
Oh and by the way, my understanding is that Sony will not be releasing an updated version of the AX100 this year.
Nick, with the couple of dives that I have used the 12-50mm lens on the GH4, I have not seen the same amount of softness in the corners at full wide.
Whilst I can't remember the numbers off hand, the GH4 in UHD mode has a different crop factor compared to 1080, something like 2x for 1080 & 2.3x for UHD plus it reads the sensor differently in the two modes so I do think the 12-50mm is better on the GH4 but sydneys conditions this last week have been not very good for wide angle shooting so it may be a little while before I can do some decent tests with this lens in the 12mm region.
Nick, I did read that the XA20 does output 8bit 422 over HDMI which is great.
I would only be recording 25fps so the 50/60p is no concern to me anyway.
Jon, yep I was thinking the extra colour space & higher bitrate would be beneficial if I can sell some of my footage to TV or use for Blu Ray etc where someone may specifically want 422 colour etc, it could give me an advantage there.
I understand the footage will look the same as the in camera footage but having the extra colour space/bitrate could help me sell footage?
I will be using a Ninja for some topside work in the future with the XA20 so it makes sense to me to house it & have that extra colour space available anyway.
I gotta say, I LOVE how small & light the XA20 is & for this type of camera it has a very nice image.
Nick, it sounds like you may be better with the DP4 if you don't want the recording option of the Ninja?
What I have found is just how useful Focus Peaking is!
I don't have that on my HVX200 & I have become addicted to Focus Peaking now:)
I really can't wait to get the XA20 underwater & see just how it goes.
The GH3 with a DP4 would be a nice compact macro rig that is for sure.
Max, I use shotput pro to transfer footage onto 2 separate hard drives simultaneously at the end of a diving day.
That way I have 2 separate copies incase of hard drive failure & shotput will give you a green light at the end of the file once it has checked that the two transfers are identical file size & numbered files.