good comments questions ... i'll do my best to answer them
nousername, when I responded to you, I was talking about the effects of a swing on a frame, and not the camera. Frames **DO** bend, even when they have not made contact with anything. Frames are made of strong materials that are able to bend and not break. A serve going 100 mph, needs to have the racquet head speeding at I believe close to 130 mph. That is **A LOT** of force, and the air causes drag and resistance, which again effects the frame bending.
yes, i knew you were addressing the effect of swing on a frame. yes, frames do bend as a result of swing, BUT it is a tiny and negligible effect. it is so small it is not noticeable. the only time the bend in a noticeable amount it during contact, AND even then it is a very small amount. btw, every material on earth can bend and NOT break. even diamond, the hardest material earth can "bend". it is simply a matter of degree. there is nothing unique about the elastic properties of racket materials. so i agree with you on that. just b/c a racket is moving at 130mph does not mean there are forces on it. accelerations, not velocities, imply forces ... good ol' sir isaac proved that one: Force = mass * acceleration. you as a human can move at 18,000 mph and have 0 forces on your body ... don't ask me, just ask any astronaut.
so .... for a serve and all other tennis shots, 99.9% of all the forces are due to IMPACT with the ball, not the swing.
As for he camera, I don't know enough to discuss. However, a few things to consider.
1. If it is the camera that is resulting in this "wobble/bend/warp" effect, then why isn't it effecting the hand and/or arm on any of the photos?? Are you suggesting the camera some how knows that it should only create this effect and only limit it to the frame head???
well, the truth is the effect IS in the whole photo. but the effect is proportional to velocity. at service contact, the main movement is the arm from shoulder to tip of racket. and the velocity is basically 0 at the shoulder and increasing towards the tip of the racket, where the max velocity is. that is why the bend is most pronounced at the tip of the racket, and is lessened as you go towards the shoulder.
2. Where does the effect of the shutter start and end on the image?? You spoke about it first capturing the top half, then bottom half, etc of the image. Again, does the camera's shutter know it is only suppose to limit this effect to wherever the racquet head is going to be i the image?? (ie: top half, bottom half, right side, left side, etc)
again, it effects the whole image. it's not top-half then bottom-half, it is simply "top to bottom". it's like a window that exposes a slit accross the sensor/film and that window slides down.
and again, it affects mainly the racket head b/c the racket head is moving the fastest.
As for the topic, and the point someone made about where is the frame **after** impact, it is surely not pointing down. In many images it is still perpendicular and moving up, or forward. It takes quite a while before one sees the frame beginning to point down. (ball not even in photo sequence any more)
Again, interesting discussion.
yes, i understood why you were presenting you pictures, but due to these photographic effects they cannot be used to prove your point. in fact, they almost prove the opposite. b/c this "skew" effect tends to bend the frame backwards ... which gives the illusion/impression that the racket is angled straight or even upward. you really need a different camera to prove it either way.
i believe the racket face is angled *slightly* downward when the ball is leaving the stringbed after a serve. AND that a "good" serve has upward racket velocity during contact.