In message , Oviedo
writes
Is it an optical illusion, eye strain, or are the props bending?


This effect can happen with focal plane (?) shutters, which are in
effect a gap moving across the film. They do not see everything at once.
Imagine the shutter opens when a blade is horizontal (at 3 o'clock) and
rotating clockwise. At that point the shutter sees the blade root. As
the shutter goes from left to right (for example), it sees the next part
of the blade in a slightly lower position. By the time it gets to the
tip, that will be at, say, 5 o'clock. The image will therefore be
curved.

See he
http://www.theaerodrome.com/forum/ai...g-propeller-qu
estion.html

Try Googling 'shutter curved propeller' or similar.

HTH
--
Peter

Ying tong iddle-i po!