I presume most of the imaging being discussed here is low power / wide field - ie I can't see anyone above talking about the optics needed for high-res planetary work...
I have a 16" f/4 newtonian and optical quality matters a lot to me :-) See this image for what is possible in good seeing, you won't get that with low quality optics...
http://www.acquerra.com.au/astro/gal...-174959utc.png
Jupiter was about 50 arcsec in diameter here, you're welcome to measure the image to see what resolving power it has. At the time this was taken I had a 14.5" f/5 mirror in my newtonian, and central obstruction about 28%.
cheers, Bird