The SCT was originally conceived as "everyman's telescope". It was designed to "do it all". And while it is very versatile, unfortunately it does nothing exceedingly well with the exception of travel. Even the Schmidt optical design is a manufacturing compromise. The corrector is ideally placed at the radius of curvature, not the focus, as every maker executes it. While this cuts the physical length of the tube in half, it also places some limits on imagery- and allows the manufacturers to sell corrective & augmentive optics as "accessories". Not to worry, the field is easily better-corrected than most fast Newtonians- just half the angular size for a given aperture. Insightful observation, Kurt. On 5/16/07, Kurt Fisher <fisherka@csolutions.net> wrote:
Although the light-weight easy-to-handle SCT package size is a big plus, one of the more confusing things to me about buying an SCT is their owners shell out for a scope with a 3000mm focal length and then immediately turn-around and spend another $200 for an adapter to turn it back into an 1100mm f/l Newt.