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.