Sensor dust across a folder

Why dust repeats

A speck on the sensor casts a soft shadow onto the same pixels every time the shutter opens. Stop down to f/11 against a pale sky and it shows on every frame of the afternoon, in the same corner. A smear on the front of the lens is similar but softer and wider. A raindrop, a crumb or a hair on a scanner bed is in one frame only.

Shade, colour casts and tilt belong to one frame's light and framing. Copy a lift from one photograph to the next and you brighten a patch that was never dark.

Fix once, replay with care

1. Open the whole card at once on Batch touch up. The first frame opens on the stage.
2. On Remove spots, Find specks proposes rings on smooth ground; on any page, tap each dust speck with Spot.
3. In the folder panel under the stage, tick only those spots. Everything else placed stays off by default.
4. Run it. Each frame gets its own disc from its own long edge and its own ring test: on a frame where the speck sits over a branch or a roof edge, that spot is refused for that frame and the row says so.

Coordinates only mean the same place on frames of the same shape. A portrait frame among landscape ones has its placed spots declined, and its row prints why.

When to stop and clean the sensor

Six placed fixes is the ceiling per photograph. If a sky shows more than six specks, the camera wants a blower bulb more than the files want tapping — and every later card will be cleaner for it.