i used the turtle on my last trip.
With the right combination strobe / cable it worked fine. I normaly use manuel mode.
I was trying with Manfred Werner from unterwasserkamera.at some things,
and he told me today that there is a known problem he heard from the turtle tecnican, with specially the Nikon D500.
I got a mail adress and will discuss this next week direct.
Something with lcd back light that causes a problem.
As soon i know more, i will write here.
worked fine for me manual on the trip.
Have the Aquatica here as well, but had not enought time to test them side by side.
Will do that and then write it down.