Below are images I've shot recently while experiminting with IR photography. The first is an IR image with +2 stops of exposure and a custom white balance based on the bright part of the tag on the fence. The second image is a shot taken 1 minute later without the IR filter, also with +2 stops of exposure and the white balance calculated by the camera.
As you can see, in the IR shot there are lots of spots. At first I thought these were dust spots but they aren't apparent in the visible light shot. What are they, and how can I avoid them?
Adjustments: Lightroom 4 (Exposure and white balance) Camera: Canon 60D Lens: Canon EF 24-105mm f/4L IS USM IR Filter: Lee Polyester 87 (730nm)