Telescope Math
Light Collecting Area:
Light collecting area is simply a measurement of the total area of a lens in order to show how much light it is capable of gathering. This is the basic equation for the area of a circle:
π (D/2)^2
Where D is the diameter of the lens
Light collecting area is simply a measurement of the total area of a lens in order to show how much light it is capable of gathering. This is the basic equation for the area of a circle:
π (D/2)^2
Where D is the diameter of the lens
Light Collecting Power:
Light collecting power is the ratio of the light collecting area of the lens in question to that of the human eye. For the purposes of this website, the diameter used for the human eye lens is 5mm. This measurement shows the relative light collecting area of the lens in comparison to the human eye:
π (D/2)^2
π (5mm/2)^2
Light collecting power is the ratio of the light collecting area of the lens in question to that of the human eye. For the purposes of this website, the diameter used for the human eye lens is 5mm. This measurement shows the relative light collecting area of the lens in comparison to the human eye:
π (D/2)^2
π (5mm/2)^2
Focal Ratio:
Also known as the f-ratio, this is simply the ratio of the telescope's focal length to the diameter of the lens. In telescopes, the f-ratio helps determine the instrument's field-of-view as well as the scale of images that it produces:
Focal Length
D
Also known as the f-ratio, this is simply the ratio of the telescope's focal length to the diameter of the lens. In telescopes, the f-ratio helps determine the instrument's field-of-view as well as the scale of images that it produces:
Focal Length
D