24P is 24 progressive frames per second, one full picture, not 2 interlaced fields. Same for 30P except 30 progressive frames per second. When you film with out either option on your filming in 60i (60 interlaced frames per second), when you deinterlace your footage on the computer its basically bought down to 30p, or if you watch it on an normal tv. I film with 30p on my camera, so i dont have to worry about deinterlacing to make my footage look better. You capture 30p and 24p normally with your camera, if you have a DVX and you film with 24pA (advance) its TRUE 24p and you need to capture differently but im not going to get into that.