Before opening
Once the board is off, the stain pattern is gone.
Restoration and repairs move fast. If nobody photographs the ceiling before the first cut, the source argument becomes memory. Memory is a poor exhibit.
Shoot the room, the stain, and a scale.
A wide shot, a close shot, and something that shows size. Include adjacent fixtures in the frame if they are part of the story.
Photograph access panels closed, then open.
A closed panel that was already wet matters. An opened panel that was dry inside matters too.
Do not delay safety for photography.
If the ceiling is coming down, get people out. Photos are for a stable or already-safe scene.
Questions people ask
Are phone photos enough?
Clear, dated phone photos are usually enough to start. Professional documentation can come later if the corporation wants it.
Should we wait for ProShield before any cut?
If the area is safe and water is controlled, waiting for a source look can prevent a random opening. If the ceiling is failing, safety wins.