Anyone use camera for collimation?
Posted 04 November 2013 - 02:50 PM
Posted 04 November 2013 - 04:32 PM
Posted 04 November 2013 - 05:02 PM
Posted 04 November 2013 - 05:16 PM
Starting with some weird Hercules webcam, then SPC900
after that DFK21 and right now ASI120MC.
Works great when you can see on screen what's happening.
Also strongly recomended to use Metaguide for
collimation, excellent tool!!
Posted 04 November 2013 - 05:25 PM
Posted 04 November 2013 - 10:15 PM
Posted 05 November 2013 - 11:12 AM
Posted 05 November 2013 - 10:33 PM
I haven't tried Metaguide for guiding, but am going to try it in the future.
Posted 08 November 2013 - 06:07 AM
Posted 08 November 2013 - 06:37 AM
In the past, if you wanted to resolve the Airy pattern, you needed to increase the f/number so it was large enough on the scale of the pixels. This is because the spatial size of the Airy pattern only depends on f/number (and wavelength). For green light, f/10, and pixels about 7um, this demanded using a barlow.
But with the new cmos cameras with small pixels, about 3.75um, you get much better spatial resolution. If you combine that with a red or infra-red filter, the Airy pattern is much larger and can be resolved at f/10 without a barlow. For faster systems you might still need a barlow, but you can always try and see.
But things are different now because you can use a red or IR filter in combination with small pixels - and still be using a real star overhead, and the full aperture of the optical system to collimate based on the in-focus Airy pattern.
Posted 08 November 2013 - 06:53 AM
So - you don't need to resolve the Airy pattern to collimate, but no matter what I would use a real star in-focus as the final indicator that you are collimated. This is described in most manuals that come with a telescope, and textbooks describing collimation.