Hello,
First me me say that cathy church is an over-rated hack. Ask her why she was kicked off the dive boat in bimini
W/ a nik V and a 15mm lens the hyperfocal distance for F/5.6 is 62 feet, at F/8 it's 44 inches. If you used the hyperfocal distance at F/5.6 everthing from 99 feet to 148 feet will be in focus. If you used the hyperfocal distance at F/8 everything from 5.7 feet to 8.7 feet will be in focus.
I have not been to honduras and can't give specifics but from a quick net search it seems to have somewhat great visibility so if this is true you could probably swing 1/250 at F/5.6. You could also set the lens on F/5.6 or F/8,set the hyperfocal distance and let the cameras meter do it's job, just pay attention to what it's telling you. Also if the hyperfocal distance is not in the subject range then move the focus scale so it is in range, keep up with the min/max indicators but try not to put the actual distance on the edge.
Reala film is awsome but doesn't hold a candle compared to proviaF but we're comparing slide film to negative film. I have shot both in the past and like both equaly as well. I use reala in my 2 1/4. What I have done is use 100iso in the am and set it for 400 iso in the pm, don't forget to mark the canister! BEFORE you load the film and have the lab do the push/pull thing. Yes I use just 100 iso film for both.
One mistake I see alot is photographers will get to far or to close from the subject with the lens they are using. With the 15mm lens many mistakes are make by not getting close enough to the subject. i.e. taking a photo of a fish 6 feet away and all you get is this big gaping area of nothing and a little small fish that doesn't show up that well. This is caused from the optical difference in the human eye and the 15mm lens. Am told the human eye is about equivalent to a 50-68mm lens or 45 degrees. The nik 15mm lens is 94 degrees, about double the angle so you can eye ball a situation, cut the distance in 1/2 and take the photo
Dont be afraid to take photo's 1 foot away from the subject either. the nik 15mm lens will focus down that close. Some slight near fill flash and the outter edges ambient looks quite nice.
Ed