rotor almost in sync with the cameras shutter.
This reminds me of the time I took a picture of an Aurora anti-submarine aircraft on take-off. That's a P3 Orion for you guys in the USA. It had just cleared the ground when I took the picture. The shutter speed was fast enough to freeze the props without any blur. Most people looking at the photo thought it was a display aircraft and were looking for the cement pillar on which they thought it was mounted. LOL