[Terry B]

Originally Posted by Ian Robinson

You can see 11th mag stars with a 60mm refractor and easily with a 80mm refractor or binos.

A 6" newt will give you stars about 13th mag I believe depending on you visual accuity and seeing conditions

http://www.twcac.org/Tutorials/limit...tude_table.htm

http://www.go.ednet.ns.ca/~larry/astro/maglimit.html

I looked at these tables.
I have reasonable eyesight and very dark skies. With my scope (200mm) I have just seen pluto when it was at mag 13.9 a few years ago. The table gives "14.0 or 15.2" as the limits for my scope size. I think the 14 is pretty close. To image a 15.2 mag star with a reasonable SN ratio would need a ~10 sec exposure minimum. I think this value is unrealistic for visual limits.