Since I sometimes go off for a week or more to shoot in the backcountry, I’ve worried from time to time about getting a dirty sensor early in the trip and not realizing it until I return… a few hundred or thousand frames later. Yesterday I ran into such a problem on a night photography shoot and didn’t realize it until I moved the photos to my computer and checked them in Adobe Bridge.

The first few shots were fine, but perhaps a half dozen into the sequence I noticed a very black smudge near the bottom of a vertical frame image. (This means it was near the “top” of the sensor when the camera was held this way.) On the next couple of shots the “smudge” moved in bug-like fashion up into the frame, finally lodging close to the middle. This was one strange dust spot – like none I’ve ever seen before. The typical spot leaves a semi-transparent smudge on the image and generally stays in one place on the sensor. (Technically, the AA filter, but you know what I mean…) This one was black and moving – at first as I cycled from frame to frame I wondered if I had a bug crawling around inside the chamber.

Fortunately, I’ve adopted a sensor cleanliness strategy that relies more on post-processing removal than on the futile attempt to keep the sensor in a pristine state of cleanliness. So far I’ve been able to remove the offending blob from all of the images from the shoot that I’ve worked on.

If there is a moral to this story, it might be this – even if you hope to keep your sensor clean, you still need to develop the post-processing skills necessary for dealing with dust specks when they unavoidably do show up.