Magic? – Midwestern Helicopter Ascends, But Blades Don’t Move
Something strange is going on here, but this is one mystery I can solve. There's a helicopter that recently took off, but the video seems to show the blades not moving? Is it magic? Not so fast. Literally.
Before I share the trick (which isn't really a trick), watch this for yourself. It's a helicopter leaving a hospital in Michigan. Watch the blades...
The woman who captured the video was astonished until "she realized that the blades were rotating at the same rate as the frame rate of the video, causing it to appear as though the helicopter was floating upwards".
Here's the math. I'm not certain this is the exact number, but let's say that the helicopter blades are rotating 24 times per second. Many movie cameras record video at 24 frames per second. That would mean that the frame rate of the camera and the rotation rate of the helicopter are in sync. While the video appears to show a magic helicopter defying gravity, it's the camera playing tricks on you.
Toward the end as the helicopter begins to accelerate (and the rate of the blades increases to more than the frame rate of the camera), you can begin to see the blades appear to move forward.
Fun with cameras and copters. You are welcome.