Those photos were taken with a film camera back in the day so Im not sure about the implications but with some of todays digital cameras with rolling shutters there is a distinct illusion. If on video mode some of your swings show a weird shaft bend , turn your camera upside down and film another swing to see if the shaft bends dramatically in the opposite direction. If it does your camera's rolling shutter image sensor is too slow for the shaft movement. It normally scans top down so turning it upside down will have it scanning bottom up and reverse the illusion.
If the image is super sharp , like a casio on burst mode its an accurate depiction. The shaft does bend, like a snake actually. Two ways , given toe down but I have photos that suggest three ways even after contact with the ground.
Threaded Mode
