This is what I got. I think tomorrow I might try them with macro.
Macro fully zoomed lens pressed against the glass no diopter used.
Regular shooting mode, with the +4 diopter, fully zoomed about 3-4" back off the tank.
God help me, regular shooting mode and the +4 and the +2 stacked about 2.5-3" from the glass (this was a bear to focus)
I'd like to say, while it seems like it, it does not magnify the coral anymore with or without the diopter, it does allow you to get closer with the telephoto whicch makes for a larger image and stay further away. Please forgive the quality, all that was done to these pics was a conversion from RAW, resize and compress, no other post processing was done.Exposure was the same in all three pics and the aperture set at f/8.