The magnification (or power) you will see through a given optical system depends on the telescope and the eyepiece. The simple formula is: Magnification = Focal length of telescope ÷ focal length of ...

This article is the third in a series teaching the basics of photography. We started by learning about the properties of light and how an image is created, and we also learned how a lens bends light ...

Watch the video: What is focal length? Take two 50mm lenses: an f/1.8 and an f/1.2. Even though they both have the same 50mm focal length, they're not the same physical length – and neither of them is ...