The Celestron CPC 925 GPS XLT telescope does not have a built-in coma corrector. It is a Schmidt-Cassegrain telescope with an aperture of 9.25 inches and is not classified as an HD model. The maximum useful magnification is about 555x. This is based on the rule of thumb that the maximum magnification is about 50 times the diameter of the aperture in inches. The telescope can be used with smartphones or tablets by adding the SkyQ Link 2 WiFi module. This enables the telescope to be controlled via a corresponding app.