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I have a webcam-like camera with a CMOS sensor and a C-mount type. And there are some filters used in astronomy that have a diameter of 1.25" type. There is adapters of course between those two mount types. When looking on Internet most of setups show a webcam with no lens, a filter mounted on it with the adapter and the whole thing is then put into a telescope. My question is how can I do that without a telescope, having just my webcam and its lens?

A setup with a DSLR camera is shown here but there again, the DSLR objective is bigger than the filter. How to do that with small webcam lens? And the filter in question is the one used in the link, for diffracting the light and do a spectral decomposition.

  • I'm not quite clear on what you are asking. Do you simply want to mount the webcam to your telescope with a filter in between? Does you telescope have a special camera port? – Chris Mueller Jun 23 '15 at 17:05
  • What is wrong with using the telescope adapter (with filter) and then not attaching it to the telescope? What is your exact problem? Can you not find an adapter that fits your camera? Are you looking to make a DIY adapter? – hazzey Jun 23 '15 at 17:57
  • @ChrisMueller I just want to take that filter and put it in front of my webcam. As it is a diffraction grating, can I just tape it in front of the camera lense somehow, or is there other things I need to consider? – Mehdi Jun 23 '15 at 22:23
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    Yes, you can just tape it to the front of the webcam lens. Try not to let any other light get in which doesn't pass through the filter. – Chris Mueller Jun 24 '15 at 10:53
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As well as the DSLR plus telephoto lens setup shown in your link, I have also used diffraction gratings mounted in front of (modified) web and video cameras as described. http://www.threehillsobservatory.co.uk/astro/spectra_20.htm Because of the very short focal length of the webcam lens however, the length of the spectrum is very short with a 100 line/mm grating. A 300 or 600 l/mm grating would be better for this type of arrangement.

  • Thats exactly what I did, using 600 l/mm or even 1000 l/mm fixed on a 3d printed case for my camera – Mehdi Jan 28 '16 at 14:54

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