I am new to astrophotography, but have been able to get some good results, mainly due to my Bortle 1 location in New Zealand.
I have a Stellarvue 80mm Doublet refractor, and Focal reducer 0.80, and my camera is a Nikon D5600. I plan to keep those for a while.
I have been shooting Unguided subs at 30 seconds exposure time and ISO-400, and stacking using Siril.
Many people say I need a Guide Scope, to take longer Subs, and I see the following options.
1. ZWO ASi-120MM-S
it has 1280 by 960 pixels and pixel size is 3.75
it has 1936 by 1096 pixels, and pixel size is 2.9
it has 1936 by 1216 pixels and pixel size is 5.86
the Cost differance between 1 and 2 is not much, but number 3 is much more expensive.
can anyone advise what would be Better ? and WHY ?