ABSTRACT
This chapter focuses on portable and less expensive systems. The focal length and mass of the optical system set the needs for the telescope mount. Long exposures and focal lengths require sub arc-second tracking, and conversely shorter focal lengths and fast apertures reduce the requirement. German equatorial mounts have the advantage of continuous tracking and once the image is centered, it is possible to image for the entire night without touching the unit. The inexpensive models are based on traditional worm drives and generally have less accurate tracking; caused by a mixture of broader tolerances, coupled with a smaller right ascension worm-gear radius. Tracking is a function of drift and periodic error (PE). Although using a short exposure can minimize drift, it is a less successful strategy for PE. The effects of seeing, PE and drift errors are additive. The coarse angular resolution when imaging with a wide-angle lens dwarfs such tracking errors.
