How to use setting circles on a small telescope (and why they don't work!)

The awkward truth about the effectiveness of setting circles fitted to small telescopes. Erratum: The scale of the AA road map referred to is in fact 1:50,000 and not 1:500. So what's another 49,500 between friends? RJD Presented by Robert J Dalby for The Astronomy and Nature Centre Produced by DB Video Services for Astronomy and Nature TV