Thanks for the info, shaker.
Have you tested the combination of the L4A tube and 6.5mm filter uw as well? Or are you satisfied with the IQ of just the L4A and Sony lens?
Sorry for the delay.
I tested the Sony lens with a the fiter too but it gives bad results underwater! I got best results with the sony lens and the Panasonic tube.
I also tested the Raynox DCR-250 Macro lense inside the Dome port, i found it performs better then the Inon UCL-165 with sharper images und much less chromatic abberation.