The ways in which amateurs may increase their chances of discovering comets were described. Amateurs discover a considerable proportion of comets, but their contribution is greater among long-period comets. The relative proportions of short-period comets is revealing: 1 in 2 for professional astronomers, 1 in 8 for amateurs. Professional discoveries are largely a by-product of searches for asteroids: the comets have low inclinations (i < 30°) and are faint (m1 > 14). Amateurs are most successful in areas close (<60°) to the Sun. Typical apertures are 150-mm, and most comets are brighter than magnitude 10.

Past results show that there is a strong correlation between number of observers and number of discoveries. Several amateurs have discovered comets at great elongations with larger telescopes (≥ 400 mm). The comets tend to be fainter (10 < m1 < 12). Several comets have been discovered with simple equipment (200- or 300-mm telephoto lenses) down to magnitude 13.

Calculations of the distribution of discoverable comets show that an average of 14 comets (9 < m1 < 14) are missed per year.