Peter Forret sent me a link to this nifty set of calculators for HDSLR film makers. This is a great way to break down this information. He has a few types of conversion calculators on his website HDSLR-Cinema. The conversions calculate frame duration, frame rate conversion, aspect ration and a few other tools.Here is a rip from the email.
Frame duration: calculate # of frames to/from duration and framerate
Frame rate conversion: calculate conversion from one framerate to another
Aspect ratio calculator: calculate megapixels, aspect ratio, letterboxing.
File size calculator: calculate megapixels, frame and video filesize estimations.
Depth-of-field calculator: calculate and visualize depth-of-field.
Composition calculator: calculate and visualize frame composition.
Light calculator: calculate required/allowed light