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 ...

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 ...

The equipment In order to capture these photos, Hamber used the following four telescopes: — SVbony 80mm aperture (450mm focal length) f/7 ED refractor — SVbony 122mm aperture (680mm focal ...

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 ...

Save over $400 on the Sky-Watcher SkyMax 180 which features in our best telescopes for seeing planets guide. With a long focal length (180mm and 2700mm respectively), its precision is almost ...

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 ...

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 ...

A telescope with no eyepiece ... Other upgrades on the previous version include a longer focal length, an improved focal ratio and a wider field of view. It now sees an area of the sky measuring ...