Hi, I’d like some advice on the minimum size of telescope I can use for photometry. I am thinking of piggy backing my 60 mm guide scope (225mm focal length) onto my C11 so I can measure the magnitude of a target star when performing spectroscopy. I would be using an ATIK 460 which has 4.56 micron pixels, so I imagine I would have to add a x 2 Barlow to the image chain in order to get a reasonable pixel scale.
The targets are generally down to around mag 12.
Is this a viable proposition? I also have a 80 mm Skywatcher Equinox ED scope with a focal length of 500mm but this is rather heavy for my setup. Thanks. John