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Pinholes in space

Thanks for the nice article on pinhole cameras in LXF281. I am an astronomer and, believe it or not I used a pinhole camera when first checking out my specialist CCD camera before attaching it to the telescope. The images from the pinhole prove that the camera and its software are working correctly.

Astrophotographers, especially those who wish to make precise measurements of their images, routinely have to deal with dust specks, vignetting, detector non-linearities, and so on. They do this through a process called flat-fielding. First, one takes an image of something which ought