Damp days can make for great prop vortices on takeoff. However, I have been feeling less than satisfied with my results recently. As I was going through some shots, I made a discovery that should probably have been something I worked out before. I like to have a good amount of prop blur so drop the shutter speed down when I can. I go with a high frame rate with the aim of getting a good sharp shot amongst the more blurry examples.
As I go through the shots, the sharp ones have okay prop vortices but not great. Then I will come across some really nice vortices but the shot is otherwise not sharp. It seems that, in panning with the plane to get a sharp shot, the trailing vortex gets blurred out. If I am not panning well, the vortex can be the thing I have tracked better and it shows up well. I have seen shots from others with the props almost frozen with a high shutter speed and the vortices easily seen.
Consequently, I am going to have to make a decision in future. How much prop blur do I want versus the ability to see the vortices well. A little trial and error will be involved. At least it is fall/winter so the Pacific Northwest will probably provide me plenty of damp days on which to experiment!