Why use a mirror instead of lens?
While standard “refractor” telescopes using lenses are highly popular, offer excellent views and are quite viable telescopes, using a mirror instead of a lens offers one very important benefit to astronomers: Large aperture at low cost. Why is aperture important? Objects in space are so unimaginably distant from us that their light is quite faint and diffuse. Large apertures naturally capture a bigger swath of light from an object than a smaller one, and focus this light into a small spot, in exactly the same way that a magnifying lens will concentrate the sun`s light. A bigger aperture multiplies the apparent brightness of an object as compared to a smaller one, allowing us to view so much more of its details. Consider that the 15cm aperture Whitey Dob 15 captures as much light as almost 460 human eyes (aperture about 7mm), letting you see many, many dozens of times deeper into the night sky than with the unaided eye. The benefits of large aperture are great, and Whitey Dob provides t
