Refractor telescopes are great for beginners ... they're not always great for astrophotography because of their curved focal plane, but for stargazing purposes they're excellent.

We installed two 20-inch PlaneWave Telescopes (CDK20, 20-inch, 0.51 meter, f/6.8 Corrected Dall-Kirkham Astrographs) on Software Bisque Taurus 500 mounts in the spring of 2017. The telescopes are ...

actively controlled beam-steering mirrors called "two-axis focal-plane choppers." These are able to steer the light entering the telescope and reflecting off its 1.8-meter (5.9 feet) aluminum ...

Because his telescope offered a much greater field of view, astronomers had plenty of room to improve magnification. One way to do that, they knew, was to make the focal length of the eyepiece ...

Dichroic beam-splitter The observatory is based around a triple-mirror telescope with an effective diameter of 20 cm, and a 11°x3.5° field of view. According to Caltech the focal plane is split with a ...

https://doi.org/10.1086/675807 • https://www.jstor.org/stable/10.1086/675807 Copy URL AbstractFocal-plane phase-mask coronagraphs, such as eight-octant phase-mask ...