@Barmaglot and @bghazzal@Davide DB actually just came back from smiling seahorse, franck the owner of the boat is one of the most passionate photographers i have had the chance to know funnily enough i knew him before he was diving professionally and did his aow-dm at my place back when i had a center ! Long story short they offer black water trips on every trip if there is enough participant, myanmar just reopened this was the first cruise and we got to do 2 bw dives. It was interesting i have yet to look at my photos, i was on the z8 and must say i was really struggling with the af in black water. I used to shoot a d500 and it was much more efficient for bw. For wa it was great for daytime macro too but for black water without 2 x 5k lumen focus light i would not get a focus and i tried many af-servo the most efficient was af-c with a large box.. i did try using my 16-35 in a 230 mm port to film for macros as well as th 24-50 with wwl1 to film but very hard to get sharpness in both cases. David i can only guess those lenses you quote were on m4/3 so maybe on fx a 50-85mm would be better provided it has short focus distance..