The f/4, f/10, or f/15 represent a telescope's focal ratio (f/ratio). Focal ratio is determined by dividing the focal length (the distance from the objective to where the light comes to a focus ...

Telescopes don't come any smaller than the Dwarf 3, but does its portability come at the cost of image quality? Read the ...

On a telescope, magnification can be calculated by dividing its objective lens's focal length by the eyepiece's focal length, both expressed in millimeters. For example, a telescope with an ...

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 ...

For budding astronomers and space experts, telescopes bridge the gap between them and space. To take your love of the planets ...

The triple objective in the micro-telescope, though of only 51/2 in. focal length, instead of the usual 8 or 9 in., successfully withstood the following severe test. At a distance of a rod ...

9.53 inch Clark Refractor The main telescope is the original 9.53 inch refractor built in 1885. The objective lens was made by Alvin Clark and Sons of Cambridge, Massachusetts, and has a focal length ...

Save 23% on what we rate as one of the best telescopes out there. It features a 102mm aperture, a 1325mm focal length, a Maksutov-Cassegrain optical design, smartphone-controlled and it comes with ...

Yet choosing the perfect telescope can be overwhelming, regardless of your astronomy experience. A quick web search will tell you to consider the scope’s focal length, aperture, eyepiece and ...