>>4325106I have experience with two cheap lenses - a 500mm reflector (HQ Optics - Korean), and a 500mm refractor (Oshiro 6/6.3 - Japanese).
The HQ lens is total crap. I get similar detail from my 120mm Nikon lens and digitally zoom in, and none of the contrast.
The Oshiro is definitely better, but it's difficult to focus. Astrophotography is easier - the lens splits light, so a star will show different colors - red-white-green - when focussing. When it's white, it's in focus. Stars still come out as circles though. Pic related, of a constellation.
