Just purchased an MX-10 and YS-40A strobe. Which film is best to use - 100 ISO or 400 ISO ? I will be using it in Bonaire in November. I assume that ISO 400 will increase depth of field but cut down on light?? Manual is not very informative.
THANK YOU!

You've got that right about the manual. It lacks quite a bit if info. I've used both 100 and 400, mostly 400 with some success. 100 is probably preferred, however I always seem to wait too late to get 100 and get stuck w/400. Try to shoot upwards to gain as much light as possible. The MX-10 does a respectable job of taking land picture, so 400 works well for that application.

Try these setting U/W with ISO 100:
Surface f16
10' f11
20' f8
40' f5.6
60' f4.5

One more thing, using the f/stop settings with the lightning bolt (the manual calls these thumberbolts (something lost in the translation I'm sure))causes the internal flash to fire increasing backscatter in the water directly in front of the lens. Not very desireable, so make sure you're not set to this when underwater.

Good luck, and post some of the keepers when you return.