Two likely causes were identified:

1. Flickering indoor lighting: Some LED lights pulse rapidly, especially when dimmed. At faster shutter speeds, the shutter exposes the sensor as a moving slit, so pulsing light can cause dark bands or partial exposure. This is more likely indoors and can vary from shot to shot.

2. Camera/shutter problem: If the same half of the frame is consistently black, especially if it’s pitch black, that points more toward a shutter, mirror, or obstruction issue rather than lighting.

How to test it:

• Shoot the same scene outside in daylight at faster than 1/250s.
• Compare that with shots indoors under your current lights.

What the results mean:

• If it only happens indoors, your lighting is likely flickering.
• If it also happens outdoors in sunlight, the camera may have a shutter/mechanical fault and should be inspected.

Normally, flash sync limits can cause this effect, but since you’re not using flash, that’s not the main explanation here.