This book demonstrates the use of an 80mm refractor and shows how it can be used as a real scientific instrument. Following step-by-step instructions users will find many activities and projects suitable for an 80mm refractor or 90mm reflector or Maksutov that have not been published elsewhere. Emphasis is on measurement and discovery activities rather than on casual observing. There are two objectives to these activities: to re-enact the process of discovery and to provide amateur observers with the knowledge and skill that will help them make genuine contributions to the field of astronomy. It is often said that users of small telescopes can conduct worthwhile scientific work, but ‘how’ is seldom explained except in the context of observations carried out by the most advanced amateur astronomers. This book provides the necessary introduction – derived from the author’s many years of experience in teaching the subject – that will be the starting point for serious work.