<P> In a telescope the objective is the lens at the front end of a refractor or the image - forming primary mirror of a reflecting or catadioptric telescope . A telescope's light - gathering power and angular resolution are both directly related to the diameter (or "aperture") of its objective lens or mirror . The larger the objective, the dimmer the object it can view and the more detail it can resolve . </P> <Ul> <Li> <P> A photographic objective, focal length 50 mm, aperture 1: 1.4 </P> </Li> <Li> <P> Diastar projection objective from a 35 mm movie projector, (focal length 400 mm). </P> </Li> <Li> <P> Two Leica oil immersion microscope objective lenses; left 100 ×, right 40 × . </P> </Li> <Li> <P> The segmented hexagonal objective mirror of the Keck 2 Telescope </P> </Li> </Ul> <Li> <P> A photographic objective, focal length 50 mm, aperture 1: 1.4 </P> </Li> <P> A photographic objective, focal length 50 mm, aperture 1: 1.4 </P>

What are the two lenses on a microscope