Sagittal Tennis

How to film your clip

A minute of setup makes every number more accurate. If one looks wrong, check your setup first.

Set up in a minute

Tripod at the side of the court, level with where you hit: 5–6 m away (about 4 m for a junior), waist height, phone sideways.

From above
Where to put the phone, seen from above Half a tennis court from above. You stand just behind the middle of the baseline. The phone stands on the side line, level with you, about 5 to 6 metres away, looking across the court at you. Crossed-out phone positions: behind you, across the net facing you, and in the far corner. NET BASE LINE shot You Phone side line, level with you 5–6 m Behind Facing you Corner
Side-on, looking across your shot. On a full court the doubles side line is 5.5 m from the centre mark: just right.
From the side
How high to put the phone Side view. The phone is on a tripod at about waist height, 1 metre off the ground, pointing straight across at you, not tilted down. A crossed-out phone up high marks filming from the stands or a fence top. level Waist height about 1 m Not from up high
Straight across, not looking down. Filming from the stands or a fence top squashes your stance and knee bend.
Check the screen
How big you should look on the phone screen Three phone screens. Good: phone sideways and you fill about half the screen height. Bad: you are tiny, under a third of the height, because the phone is too far away. Bad: phone held upright, which leaves you small in the picture. About half the screen height Too far away under a third Phone upright you end up small
Stand where you'll hit and look before you press record. You should fill about half the screen height, with room either side for the racket.
  1. Tripod on the side line, level with where you hit.
  2. Phone at waist height, turned sideways, on the normal 1× lens (not the 0.5× wide one), pointing straight across.
  3. Stand where you'll hit and check the screen: about half its height, racket room either side.
  4. Press record and leave it: no zooming, no moving the phone.
  5. Hit 8 or more shots. The more shots, the less one odd one moves your scores.
A floodlit court at night, filmed from the side with the phone sideways. The player is mid-forehand, whole body in shot with room around the racket, filling about 40% of the picture's height.
Like thisPhone sideways at the side of the court. The whole body is in shot with room for the racket, and the player fills about 40% of the picture's height.
A night court filmed from far away. The player is a small figure in the distance.
Too far awayToo small for the tracker to follow.
An indoor court filmed from behind the baseline at an angle. The player is serving with their back half to the camera.
From behind, at an angleStance width and knee bend get squashed, and the body hides the racket arm.
Why: filling 40–50% of the screen height, the player is tracked reliably. Below a third, tracking starts to drop out. On a normal phone lens that's about 5–6 m away. Filming a junior? Move closer, to about 4 m, so they still fill 40% of the height.

Camera angle

Do

Film side-on: at a right angle to the ball's path, level with where you hit.

Avoid

Filming from behind, from a steep diagonal, or from the stands looking down.

Why: side-on keeps stance and weight transfer in the plane one camera measures well. From behind or at an angle they get squashed, and the numbers drift.

Film in landscape (phone sideways)

Do

Turn the phone sideways before you press record.

Avoid

Filming upright (portrait).

Why: a swing reaches out sideways. Portrait is too narrow for the racket at full stretch, and leaves the player small.

Keep the camera still

Do

Tripod, fence clip, or the phone braced on something solid. Set the zoom once.

Avoid

Handheld, walking, or zooming and panning mid-swing.

Why: camera shake can hide a real shot entirely and shift scores even when tracking is fine. A still camera is the most valuable thing you control.

Framing

Do

Whole body in frame for the whole swing, feet to head, with room for the racket. Stand upright for a moment somewhere in the clip; between points is fine.

Avoid

Cutting off feet or head, or filming so close a limb leaves the frame mid-stroke.

Why: every distance (stance width, contact height, weight transfer) is scaled from your height, measured while you stand upright and fully visible. No such frame, no reliable scale.

Lighting

Do

Good daylight or a well-lit court, with the light behind or beside the camera.

Avoid

Filming into the sun or a bright window. It turns the player into a silhouette.

A few smaller things