How to film rowing for video analysis

1. Film side-on, square to the rower. The camera should look straight at the rower's side, not from in front, behind or at a diagonal. Joint angles are measured in the plane of the image, so past about 20–25° off side-on they start to distort. The capture check warns you when that happens.
2. Put the camera level with the hips. On the erg, that's a phone on a chair or a stacked erg. On the water, it's level with the boat, not looking down from a bank.
3. Get close enough that the rower fills most of the frame. Keep the whole body in shot, hands to ankles, at full reach and at the finish. A small figure in a wide shot loses the joints that matter.
4. Keep the light behind the camera. A window or low sun behind the rower turns them into a silhouette, and silhouettes track badly. Glare off the water does the same.
5. Record at least five or six unbroken strokes at steady pressure. More is better. A full piece lets the performance score measure how technique holds up as you tire.

• Stand the phone in landscape so the whole slide fits, from the front of the rail to the back.
• Keep the feet in shot. On the erg, the capture check requires them, because shin angle and knee compression depend on the ankle.
• On a crowded erg floor, move the camera closer rather than zooming in. Other rowers crossing the frame can confuse tracking.
• If you use the iPhone app, the capture wizard walks you through the set-up and sends the clip straight to analysis.

What gets graded from that clip is covered in erg technique analysis.

• Film from a launch matching the boat's speed, or from a dock or bank as the boat passes square to you.
• Don't worry about the legs. On-water mode marks joints hidden by the hull as unmeasured, and feet aren't required.
• For crews, keep the whole boat in frame from bow to stern so every seat can be tracked.
• Film on the side the sun is on, so the rower is lit from the camera's direction.

What's different about grading in a boat is covered in on-water rowing video analysis.

• Normal video mode is fine. Clips are normalised to 30 frames per second for analysis, so slow-motion modes don't add accuracy and do make the file bigger.
• Trim to the strokes you want graded. The free plan takes clips up to 30 seconds, Pro up to 2 minutes, and Elite has no length cap.
• Hold the camera still, or use a stand. Panning to follow the rower is fine; shaking isn't.

Mocta-X won't publish a technique score from a clip it can't measure. You need at least half the frames usable, at least three gradeable strokes, and a passing capture-quality check covering angle, distance and (on the erg) feet in shot. When a score is withheld you're told which of those failed. It's almost always the angle or the distance, and a re-film fixes it.