Telescope Calculator

AperturePlease enter the aperture of your telescope.mm ( " )
Focal LengthPlease enter the Focal Length of your telescope.mm
Focal RatioPlease enter the focal ratio of your telescope. f/

Please select one of 458 telescopes from the drop-down box, or use Manual mode to enter the aperture and focal length by hand.

BarlowA Barlow Lens increases the magnification of an eyepiece by adding additional lenses into the lightpath. Factor x 

Please use the multiselector to choose your eyepieces from a selection of 1559.

Zoom Eyepieces are grouped at the bottom of the list.

Multiple eyepieces can be selected.

If you hold the [SHIFT] key down then click, a range of eyepieces will be selected.

If you hold the [CTRL] key down then click you can select multiple individual eyepieces.