SingAstro

Hi, I'm new in astrophotography and as part of my upgrading for astrophotography equipment, I come across the Vixen GA-4(1.25" version). It give the following infomation for calculating the focal length of telescope or telephoto len using a guide scope of 1000mm focal length: 1st 2nd 3rd 4th 5...

Thought I will just drop a line here to inform members about this little-known brand of 'home-made' eyepieces... I own one of these budget line of eps, and have looked through a couple others before. IMHO, they offer a good mix of price, performance, field-of-view (usually 70deg), and eye-relief. F...