Put the camera to the side of you!

[NLBwell]

Put the camera to the side of you when showing your strokes for review. You can't tell much at all from a view from behind (unless the problem is something like the toss wandering left or right). It is very difficult to tell important things like where the contact point is in relation to your body, the rotation of the legs, hips, trunk, arm, etc. and how those things are coordinated with your timing. You can't tell how far the hips are moving versus the legs on a serve, or how the upper body and arm are rotating over. The view from behind is about the worst view possible for telling anything useful about your body mechanics.
Where the ball goes doesn't change your body mechanics!
Do you want someone analyzing your mechanics or just going, "good, the ball went in."

 

[WildVolley]

Not true.

For the best analysis, you probably want multiple angles. On the serve, the side view can tell you about toss location and body lean, shoulder angles, etc. However, the rear view can show you whether the arm is straight at contact, and better shows the important angle between the arm and racket at contact.

While I realize you were responding to another thread, the best camera position depends upon what you're trying to see. Multiple camera angles are the best.

 

[Chas Tennis]

Some camera viewing angles for the serve.

All positions may show better some interesting feature of the tennis strokes because they are so 3D. Tennis is more 3D than golf.

I believe that Rozroz just placed a smartphone with its wide angle lens on the ground. Very useful video. The first picture was typical of the HD video image sharpness. The bright sunlight resulted in very small motion blur. Very informative but to compare it to other high speed videos is difficult.

Hand held, arms high with camera, standing behind server, viewing along the trajectory but a little low. Because of a fast shutter speed and 240 fps frame rate the rotations of the ball could be seen. Rotation was 3600 RPM.

https://vimeo.com/92106325

Overhead View. The camera directly above is best because overhead videos are so very rare. FYB created the best videos from above. Toly has made some very informative composite pictures and videos from them.

Camera Views Along & Perpendicular to the Ball's Trajectory. To get some experience in how strokes look in high speed videos, I believe that it is best to limit the camera viewing angles. I like camera viewing along the ball's trajectory and also viewing perpendicular to the ball's trajectory. That is different than from 'the side', usually parallel to the baseline, and 'behind' which is not defined but could mean looking along the court centerline. That's often done so that the camera does not have to be moved.

For the serve, being behind the server and looking along the court's centerline is not the same as viewing along the ball's trajectory.

Trajectory Differences Ad & Deuce Sides. The ad and deuce serves have too much difference in direction to not re-point the camera. Using a protractor and copy of the court - balls to the centers of the ad and deuce service boxes have trajectories that are roughly 24° apart. For wide serves the angles could be as much as twice that, maybe 40-50° different. That is too large an angle for comparing serves from the deuce and ad courts without re-locating the camera. Of course, you can't eliminate the variation in the ball's trajectories from serve to serve.

Camera Height for Serve to View Along Ball's Trajectory. For height and looking along the trajectory, the fence is about 10' high and is pretty good but the fence is not high enough to look directly along the trajectory of a 6' tall server. To get a better angle you can use a ladder and move closer to the server. Clamping a tripod, with a geared elevator and adjustable head, to anything is an advantage because the camera's head is designed to adjust the camera's pointing angle.

 

[sez]

What if you are not capturing serving and just general strokes. Is it better to use a side view? This is the angle I used for my thread. Should i just put it on a baseline pointed at me.

https://www.youtube.com/watch?v=CRW2wak_Aic&list=UU10YEognNCtUsbpaIrVq8Qg (2:33)

https://www.youtube.com/watch?v=TrHcDaXjOOA&list=UU10YEognNCtUsbpaIrVq8Qg&index=1 (3:30)

 

[Chas Tennis]

What if you are not capturing serving and just general strokes. Is it better to use a side view? This is the angle I used for my thread. Should i just put it on a baseline pointed at me.

https://www.youtube.com/watch?v=CRW2wak_Aic&list=UU10YEognNCtUsbpaIrVq8Qg (2:33)

https://www.youtube.com/watch?v=TrHcDaXjOOA&list=UU10YEognNCtUsbpaIrVq8Qg&index=1 (3:30)

Both views are very useful. What do you want to see?

How closed is your racket at impact?

http://blog.tennisspeed.com/2011/05/roadmap-to-hall-of-fame-forehand-part-1.html

The view from behind will show less motion blur in a given light level because the racket is moving away from the camera and not across the frame. High speed video becomes more necessary for viewing the racket from the side, because of the distance that the ball and racket move in the time between frames.

Side views may risk the camera from a ball hit on the camera or tripod.

 

[sez]

so a 60fps video like the one i captured is useless for side capture because of motion blur?

I get that for breaking down a particular stroke you probably need a side view, but for a general overview of a player and identifying where improvement is needed a back camera positioned moderately high enough is fine, right?

 

[Chas Tennis]

so a 60fps video like the one i captured is useless for side capture because of motion blur?

I get that for breaking down a particular stroke you probably need a side view, but for a general overview of a player and identifying where improvement is needed a back camera positioned moderately high enough is fine, right?

No, 60 fps is very useful for limited stroke analysis even while watching a match. 60 fps is especially useful if the motion blur is small.

Look at your largest motion blur from behind with the poor lighting.

This excessive motion blur makes any analysis of the stroke impossible. You can see the slower body motions/positions, some footwork, etc.

In direct sunlight, the motion blur should be much smaller. That's because sunlight has about 100X as many photons and your camera's automatic exposure control will select a faster shutter speed.

From the side, video your forehand in direct sunlight to see the motion blur. Use the widest angle zoom lens setting available, the 'fastest' lens. That shows the smallest motion blur that your camera is capable of.

 

[Lukhas]

so a 60fps video like the one i captured is useless for side capture because of motion blur?

A 60fps video will have less motion blur because of the higher fps. More fps equals less need for the camera to compensate with blur to make the video look somewhat smooth.

 

[sez]

A 60fps video will have less motion blur because of the higher fps. More fps equals less need for the camera to compensate with blur to make the video look somewhat smooth.

Is 60fps sufficient though because some of the high end high speed cameras are capable of a lot more. What is the ideal fps for breaking down a serve for instance?

 

[Chas Tennis]

Is 60fps sufficient though because some of the high end high speed cameras are capable of a lot more. What is the ideal fps for breaking down a serve for instance?

At a speed of 100 MPH an object moves 1760" per second.

The distances moved between frames by a 100 MPH object moving across the frame or up and down, recorded at various frame rates are:

at 30 fps 1760"/sec X 1/30 sec = 59"

at 60 fps 1760"/sec X 1/60 sec = 29"

at 120 fps 1760"/sec X 1/120 sec = 15"

at 240 fps 1760"/sec X 1/240 sec = 7.3"

at 1000 fps 1760"/sec X 1/1000 sec = 1.8"

240 fps, or a frame every 4.2 milliseconds, shows motions of the body, racket and ball very well and usually catches the ball on the strings. If you want to see the ball move on the strings 1000 fps will get you about 4 frames. 2000 fps about 8 frames. etc.

For more details on movement between frames and motion blur see the first reply -
http://www.kinovea.org/en/forum/viewtopic.php?id=435

 

[Chas Tennis]

sez, what camera are you using?

 

[Chas Tennis]

....................... The view from behind is about the worst view possible for telling anything useful about your body mechanics.
...........................................

A camera view shows the object's position components both across and up and down in the frame pretty well. But the component toward and away from the camera is not well shown. You first decide on what you most want to see and then pick your camera view.

A view from behind shows the position of the ball on the racket string face best.

Serve. The view from behind is excellent for showing internal shoulder rotation on the serve during the last 30 milliseconds before impact.

The side view obscures ISR and has misled most people for decades into seeing the arm swing but not the arm rotation.

The rare overhead view is probably best for showing many important things on the serve. Shows - racket motion, hand path, ISR, differences among the types of serves, upper body more to the right for the kick serve, impact location, where the eyes are looking at impact......... Thanks to FYB and Toly showing us this great new camera view!!

................................................
Here are FYB Frank Salazar different serves. .............................................

For ground strokes, the side view (body not blocking) is excellent for the overall stroke. The camera has to change sides to best show the forehand and backhand because the body blocks impact. For seeing how the racket contacts the ball in a high speed video closeups both the side and behind views have are probably very useful.

Two high speed cameras, one behind and one to the side, would be a big improvement for high speed video analysis of strokes.

 

[sez]

sez, what camera are you using?

GO Pro h3+ captures in 1080 at 60fps.

 

[Chas Tennis]

GO Pro h3+ captures in 1080 at 60fps.

120 fps Go pro 3 tennis video from the side.
https://www.youtube.com/watch?v=T9XrhpjiriQ

Some video was taken in overcast (with no shadows) and some in direct sunlight. Motion blur is small.

The camera or tripod could be hit by a ball when rallying with a player or by a ball from a side court. Less chance with a ball machine. Protect the camera from hit or fall with bubble wrap, etc.? Will it take a hit and fall to the court and be OK?

Your video is not very very sharp, lighting, Youtube conversions, what? Nothing seems to be in focus.

 

[Lukhas]

Is 60fps sufficient though because some of the high end high speed cameras are capable of a lot more. What is the ideal fps for breaking down a serve for instance?

If it's for your personal use, the more fps you can afford the better. It also depends if you're planning to upload it on a streaming platform or not. YouTube now accepts up to 60fps, so that'd be the maximum in real speed. Generally super slow-motion footage is in 240fps, so if you wish to look at your serve in super slow-motion 240fps would be the minimum. A camera that allows the shutter speed to be set in some way would also be beneficial in order to have less blur.

 

[KineticChain]

slow motion isn't good for people who aren't seasoned coaches. there's already enough misconceptions and terrible analyses on here with normal speed. slow motion completely muddles up your perception of which muscles are being used and which are not if you don't know what you're looking for. you see the end product more clearly, but you don't know how it got there