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Astrophotography with webcams

Astrophotography with webcams. Astrophotography. Traditionally done using film or CCD Film is typically cheaper than CCD, but there trial and error is often involved if you have no guidance or prior experience CCD is usually too expensive for the budget of a typical beginner

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Astrophotography with webcams

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  1. Astrophotography with webcams

  2. Astrophotography • Traditionally done using film or CCD • Film is typically cheaper than CCD, but there trial and error is often involved if you have no guidance or prior experience • CCD is usually too expensive for the budget of a typical beginner • Webcams can be a cheap alternative, providing some of the advantages of CCD, but at the cost of film

  3. Webcams for Astrophotography • Easy to use for “one shot color” pictures of bright objects such as the planets. • Can record images at higher frame rates than most CCDs, can be good for timing astronomical events, or imaging fast moving objects • Inexpensive compared to other options

  4. Imaging bright objects with unmodified webcams • Main challenge is to mount the webcam at the focus of the telescope • Many webcams have easily removable lens assemblies • A barrel from a broken eyepiece is perfect, a used film canister is workable, but not quite as nice • Tape is your friend, though machining a custom mount is best of course

  5. Finding objects • Finding planets is easy, they are very bright. When defocused a bit, they are VERY easy to center in the webcam view • Finding dim objects can be much harder, in which case a parfocal eyepiece or eyepiece+barlow can be very handy • If parfocal eyepieces aren’t good enough, a “flip mirror” may be necessary.

  6. Focusing • Focusing is hard • Poor seeing can make it even harder • The CCD chip must be aligned flat in the focal plane of the telescope, or images will always be partially out of focus • Tape can also be your enemy; it stretches, wiggles, expands, and shrinks with temperature, thus affecting focus.

  7. Exposure adjustment + compression • Tricky to set exposure to get both dim and bright objects (i.e. Jupiter + Moons..) • Use uncompressed or lossless compression file formats for original images, so that you can get best processing results later

  8. Image processing, better pictures • Adjust brightness • Increase contrast • Sharpen images • Stack multiple images together to get better images than any single image • Pick the best images from a movie, or from a sequence of exposures, stack only the best images to create a new image

  9. Modified long-exposure webcams • Webcams can be modified for long exposures with some soldering and careful circuit assembly • Long exposures are absolutely necessary in order to image dim objects • Still cheaper than buying a commercial CCD camera, or even a kit.

  10. Other uses for astrocams • Can be used for software-based autoguiding with normal CCD or film-based astrophotography • Measuring light pollution by computer, sky brightness, etc. • If camera mods are non-invasive, can still be a webcam! 

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