macOS camera permission

Beam Bench sees the camera in the device list but capture fails or shows a permission error.

You see

The Camera panel shows your camera in the Device dropdown, but selecting it produces:

A blank or missing captured frame.
An error about camera permission.
A macOS prompt that you may have missed.

macOS requires explicit user consent before any app can read from a camera. The first time Beam Bench tries, the system prompts. If you said no, or the prompt was missed, the camera is permanently denied until you re-enable it manually.

Fix

Grant permission via System Settings

System Settings → Privacy & Security → Camera.
Look for Beam Bench in the list.
Toggle it on.
Quit and re-launch Beam Bench (the permission only takes effect on next launch).
Re-select the camera in the Camera panel.

If Beam Bench is not in the list at all

This means Beam Bench has never asked for permission. Possible causes:

You have not opened the Camera panel.
The panel opened but the camera-selection event did not trigger the OS prompt.

Try:

Open the Camera panel.
Pick a camera from the Device dropdown.
A macOS prompt should appear. Click Allow.

If no prompt appears, the camera framework may have an issue. Restart the app, restart the machine.

If permission is granted but feed is still blank

Another app may have the camera open. macOS only lets one app capture at a time. Close FaceTime, Zoom, Photo Booth, OBS, etc.
The camera itself may not actually be working. Test with Photo Booth, if Photo Booth also shows nothing, the issue is the camera hardware or driver.

Verify it worked

The Camera panel captures a frame when you click Update Overlay.
Beam Bench is enabled under System Settings → Privacy & Security → Camera.

Still stuck?

Camera panel reference.
Camera not detected: for cases where the camera does not appear at all.
Post in the Facebook group with the macOS version and camera model.