Andrew, might be a good idea to add this link on Fencecheck.

http://www.fencecheck.com/forums/index.php/topic,772.0.html

As RPMs and number of blades has something to do with your shutter settings.

SP 1/100



Also might want to add a blip about how helo's are harder to get the prop blur down due to the rear rotor turning much faster than the main rotor.