Planetary observers work endlessly to improve the definition of telescopic images of the Moon and planets. While using filters will not eliminate optical defects in the telescope they will help improve image definition even in a bad system.
IMAGE definition in a telescope is dependent upon resolving power, contrast, and sharpness. Resolving power is primarily a function of aperture; however, optical quality, collimation, tube currents, etc., can have great effects. IMAGE sharpness is a factor of "astronomical seeing," atmospheric scattering, irradiation in the eye, and the condition of observer's eye. Contrast is the difference in brightness between areas of an image. Each of these factors can be improved upon by the use of filters at the telescope.
