For video and ambient light shots the best entry level set up is panasonic lx7 in nauticam housing with a wetmate dome
Priced at $1500 in US and £1150 in UK because of VAT
The Sony is best for stills but at 1080p the additional benefit of the large sensor are not visible instead the sharper lens of the panasonic gives better corners
Plus with the lx7 you can take good close ups without any wet lens
Right now for me the LX7 is the best for video and the RX100 best for stills
I have tried both so I can speak from experience
I have few videos one youtube channel with both cameras and clearly the image quality is the same with the lx7 sharper and brighter
For stills the 20megapixels of the Sony and the small aperture used with strobes kill any other compact but the lens is basic and not bright when you shoot ambient light you can effectively shoot the lx7 at iso400 instead of the iso800 of the Sony
Another feature very useful for video with the lx7 is the neutral density filter so if you have to shoot the sunball is like you had f/22 not only considering the base ISO of the Sony is 125 and the lx7 is 80 you are talking about 2 stop and 2/3 darker for the lx7
If you can shoot at 1/100 ISO 80 f/8 with ND filter with the lx7 the rx100 would be 1/800 iso125 f/11 which means scatty footage
Sony has omitted an ND filter even on the MKII
Priced at $1500 in US and £1150 in UK because of VAT
The Sony is best for stills but at 1080p the additional benefit of the large sensor are not visible instead the sharper lens of the panasonic gives better corners
Plus with the lx7 you can take good close ups without any wet lens
Right now for me the LX7 is the best for video and the RX100 best for stills
I have tried both so I can speak from experience
I have few videos one youtube channel with both cameras and clearly the image quality is the same with the lx7 sharper and brighter
For stills the 20megapixels of the Sony and the small aperture used with strobes kill any other compact but the lens is basic and not bright when you shoot ambient light you can effectively shoot the lx7 at iso400 instead of the iso800 of the Sony
Another feature very useful for video with the lx7 is the neutral density filter so if you have to shoot the sunball is like you had f/22 not only considering the base ISO of the Sony is 125 and the lx7 is 80 you are talking about 2 stop and 2/3 darker for the lx7
If you can shoot at 1/100 ISO 80 f/8 with ND filter with the lx7 the rx100 would be 1/800 iso125 f/11 which means scatty footage
Sony has omitted an ND filter even on the MKII