|Albert van Duin
| How do the images of an 0.4m amateur telescope in a back garden in Beilen (at 10m above sea level) compare to those of the 2.5m Sloan Deep Sky Survey telescope on a 2788m high mountain top in New Mexico?
During the first clear night in 2016, 22 integrations of 600 seconds were made through LRGB filters with a 0.4m telescope in Beilen. Those images were calibrated and combined into a colour image, which in its turn was aligned with an image made by the Sloan Digital Sky Survey, so they could easily be compared. The field contains several galaxies and a planetary nebula (PGC10427)
Beilen Digital Sky Survey: 0.4m telescope, 0.126 m2 collecting area, 10m asl, total exposure time 220 minutes
Sloan Digital Sky Survey, 2.5m telescope, 4.9m2 collecting area, 2788m asl, total exposure time 5 minutes
The most prominent difference is the better sharpness of the SDSS image, probably due to better seeing conditions at the mountain top and the better resolving power of the bigger telescope. Also the SDSS sensitivity is higher, due to the 38.9 times larger collecting area of the telescope mirror and the much darker sky background.
Still, with a bit of patience, an amateur can image very faint objects. By making even longer integrations, I've been able to reach magnitude 22.4 so far.
The full field can be seen at: http://www.astrobin.com/231418/B/