Test for apochromatic level of your scope.

This image, taken through a William Megrez II ED, has been cropped to produce a photo apparently taken with a 1680mm telephoto lens attached to a 35mm camera(560mm fl scope times 1.5 CCD mag. times 2 for crop). This image displays very good correction for all primary colors. Tree leaves and twigs against a pure blue sky is an excellent subject for this type of test.

Attached Image:

Agreed, it looks pretty good for imaging. Twigs against
sky do not show any bleeding of blue/violet into dark
areas.

A visual star test at high power would be a much
stronger test, but there is probably no point, unless
you plan a lot of planetary viewing.