A rear camera is a different tool once the lens is wet

A rear camera on a dry afternoon is a generous tool. The kerb is in the picture, the lines are bright, and the beeps agree with what you see. After rain it is a different tool. The lens beads, the picture goes soft, and the kerb you need is the thing the water hides.

The picture was on. The kerb was not.

On a wet motorway morning the desk backed two cars into the same marked bay. Both screens woke. In the first, the white line was still a line. In the second, the lens had a film of road spray and the line had become a pale smear near the bottom of the picture. The sensors still sang. The picture did not earn the trust the dry-day version had taught us to give it.

Wiping the lens with a thumb brought the line back. That is a boring fix, and it is the whole story. A camera behind a tailgate lives in the spray. If the desk cannot see the bay, we do not pretend the bay is where the last dry picture left it.

What we will write down

From here a weather note includes the lens, not only the wipers and the road. If the picture is clear, we say so. If it is a grey wash and the car still offers it as guidance, we say that too. No model score. A wet lens is not a feature, and a dry one is not a permanent condition.