* Astronomy

Credit eyesontheskyDOTcom

Hosted by David Fuller of "Eyes on the Sky," this video covers the the three basic types of amateur astronomy telescopes: Refractors, reflectors and compound telescopes. It gives an overview of each one, as well as comparing and contrasting the advantages and disadvantages of each type of design. An excellent primer for anyone wanting to understand more about telescopes.

This video discusses the basics of telescope magnification and focal ratio. 

Hosted by David Fuller of "Eyes on the Sky," this video goes over the various sizes and types of basic eyepieces for many amateur telescopes. The three most common eyepiece barrel diameters are discussed, as well as the types of lens configurations which determine how well the eyepiece forms an image for the user - including the concept of eye relief which can matter a lot to those who wear eyeglasses. Discussed are Huygens, Ramsden, Kellner, RKE, Modified Achromat, Plossl and some advanced designs, plus some information about anti-reflection coatings. An excellent primer for anyone wanting to understand more about telescope eyepieces.

This video about the basics of telescopes discusses field of view, in particular, the difference between apparent field of view (AFOV) and telescopic field of view (TFOV). With an explanation of the math used to calculate these plus various examples of the calculations and visuals, the viewer can finish this video with a more complete understanding of this concept that is often confusing to beginning amateur astronomers who are new to telescopes.

Barlow lenses are an inexpensive - and often effective - way to increase the magnification and eyepiece collection of amateur astronomers. In this video, David Fuller of "Eyes on the Sky" takes the viewer through the various types, caveats and benefits with using them, as well as what to look for when shopping for one.