[Kellycat]

"Personally, I like to use 1 stop increments. That means that if the brightest exposure (the shadows exposure) is 8 stops slower than the darkest exposure (the highlights exposure) then you'll need 9 files, each a stop apart. Sometimes I resort to 2 stop increments. Since I usually manually set the exposure increment in Photomatix (I use 16 bit tiffs) its easy to remember the interval if its consistent."

Thanks for that info. Much Appreciated.