Telescopes & Equipment

An altazimuth mount (alt-az) moves in altitude (up-down) and azimuth (side-to-side), like a camera tripod.

Aperture is the diameter of a telescope's primary light-collecting element (lens or mirror), the single most important s...

A Barlow lens is a negative (diverging) lens placed between telescope and eyepiece to multiply magnification, typically ...

Binoculars offer wide-field, two-eyed viewing ideal for casual astronomy, comet hunting, and surveying large sky regions...

Cassegrain telescopes use a primary mirror that reflects light to a convex secondary mirror, which reflects it back thro...

Coma is an optical aberration in parabolic mirrors (like Newtonians) that makes off-axis stars appear as tiny comets poi...

A Dobsonian mount is a simple altitude-azimuth mount using Teflon bearings on a rotating base, revolutionizing amateur a...

Equatorial mounts align one axis parallel to Earth's rotation axis, allowing simple tracking of celestial objects with s...

An eyepiece is the small optical system at the telescope's focus that magnifies the image for viewing, essentially a sop...

A field flattener is a corrective lens that eliminates the curved focal plane inherent in many telescopes, producing sha...

Specialized filters block light pollution and enhance contrast for emission nebulae by isolating specific wavelengths.

A finder scope is a small, low-power telescope or sighting device mounted on the main telescope to help locate objects i...

Focal length is the distance from a telescope's primary lens or mirror to the point where light converges to form an ima...

Focal ratio is the telescope's focal length divided by its aperture (f-ratio = focal length / aperture diameter).

Go-To mounts use computerized motors and databases to automatically locate and track celestial objects, dramatically sim...

A guide scope is a small telescope piggybacked on the main imaging telescope, paired with a camera to provide real-time ...

A space telescope launched in 1990.

Light pollution filters selectively block wavelengths from artificial lighting (sodium, mercury vapor) while passing sta...

Maksutov-Cassegrain telescopes use a thick meniscus corrector lens instead of Schmidt's aspheric plate, creating compact...

The Newtonian design uses a parabolic primary mirror at the tube's base and a flat secondary mirror near the top to refl...

Reflector telescopes use curved mirrors to collect and focus light, offering the most aperture per dollar.

Refractor telescopes use lenses to bend (refract) light to a focus, the classic "spyglass" design.

Schmidt-Cassegrain Telescopes (SCTs) combine a Schmidt corrector plate at the front with Cassegrain optics, creating a v...

Solar filters provide the ONLY safe way to observe the Sun through telescopes or binoculars, protecting eyes from perman...

A star diagonal is a mirror or prism at 90° that redirects the light path, making viewing more comfortable by positionin...

A T-ring is a camera-specific adapter that attaches a camera body to telescopes via the standard T-thread (M42×0.75mm) m...