YS-90DX - Which power setting for macro?

I have recently bought a used YS-90DX for use with my second Nikon D50 in a Fantasea FD50 housing, which lacks TTL possibilities. I wonder which light level setting(s) (with the camera at ISO 200) people find suitable for macro.

There are exposure tables on page 12 of this manual or use a guide number around 11 (m @ 100 ISO) underwater

http://www.seaandsea.com/PDF_manuals/YS90DX.pdf

There are exposure tables on page 12 of this manual or use a guide number around 11 (m @ 100 ISO) underwater

 

http://www.seaandsea.com/PDF_manuals/YS90DX.pdf

THanks Balrog! However, I am sceptical of the table as my ewperience with the YS-90 Duo (same GN) is that half power at F22, ISO 200 (lowest setting on the D50), gives a grossly overexposed image at a distance of 0.2m.

The light output of the YS90, 110 & 27 is essentially the same. For macro I usually start at 1/2 power, then adjust for the f-stop range that I prefer to shoot (f11-22). Some shots may require only 1/4 power.

The light output of the YS90, 110 & 27 is essentially the same. For macro I usually start at 1/2 power, then adjust for the f-stop range the I prefer to shoot (f11-22). Some shots may require only 1/4 power.

Thanks jc!