I have recently received a number of messages asking me why I am not upgrading to a micro 4:3 set up.
There are several reasons why I am not doing that even if my photo rig is nearly as heavy as a micro 4:3 or even a DSLR and have to do mostly with video not with stills.
I will try and touch on the key points in this post, please remember those are subjective and by no mean a criticism to other people that use 4:3 set up for video.
Note: my perspective is one of a typical non professional user that has limited time to get the best shots. This is not an absolute point of view it is clear that if you are a ‘pro’ and have much more time to spend to get few seconds of footage many considerations do not apply.
The way I have learned to love underwater video is the composition opportunities that it gives. My main source of inspiration is John Boyle and his book that remains the only valid handbook for what I am concerned even if it is a little old.
One of the classics of underwater video is the sequence: wide-medium-close-super close. On a micro four third in order to have good quality you would choose a macro lens or a wide angle lens, both those choices will prevent a number of shots you either do close and super close or wide and medium and maybe close but not super close.
With a camera with a fixed lens with a range of 28-100mm and wet lenses you can cover the whole spectrum of shots although you may need to swap lenses during the shot the possibility is there.
Some users try to use one lens to catch all, usually the choice is a Panasonic 14-42mm or an Olympus 12-50mm. However this is not as exciting as it seems in the first place. I have run some comparisons on the optics on DXOMark assuming the 4:3 are on a Panasonic GH3 that really is a mini SLR you can see the results by yourself
The RX100II gives better quality than both those lenses and especially it does it at f/1.8 versus the f/3.5 of f/4 of the other lenses.
The RX100 does have issues of distortion and chromatic aberration at the edges because of the extensive correction but is overall sharper at wider aperture. This is very important for video that is shot at ambient light.
You can add M67 lenses to the Panasonic 14-42 and the 35 macro port (am talking about Nauticam ports here) the results will be worse than the RX100 as the starting point is worst. There is no M67 mount to use the Olympus 12-50mm lens, I will try to see if the flip diopter can do that without vignette but still this gives only 24mm against the 18mm of the RX100 with an Inon wet lens.
The only cameras that are decent are Panasonic as Olympus video is pathetic. However only the GH3/4 have anything better than a compact in terms of recording formats. The new Sony RX100 Mark III with 50 mbps 24/25p seems almost equally interesting.
Micro 4:3 cameras do not have in camera stabilization in video mode and most of the lenses (the 14-42 is an exception) do not have optical stabilizers to contain costs. It follows that close ups are shaky and even wide angle has jumps.
With all the considerations above it follows the only real set up would be a lens with a stabilizer, the only available that can also shoot close up with a wet lens is the 14-42mm Panasonic. However this lens seems to have worst optical quality than the on-board lens of the RX100II (I have checked some real life shots myself). The only benefit left is the higher bit rate recording format and this is only if you go on a GH3/GH4, with higher recording formats available for the RX100 Mark III and with an announced Panasonic LX8 with potential 4K I personally do not see a reason to jump on the 4:3 wagon for video. I do believe though that if you take mainly stills there is a compelling reason for 4:3 as you can have one camera fitting almost everything and smaller to pack than a DSLR (but not that much and forget about 200-400mm f/2.8 tele lenses).