**Notes:**

1: Atmospheric seeing conditions (the sky) often limits the maximum usable magnification to 250-350x.

2: An exit pupil size (diameter of light beam as it exits eyepiece) over 7.5mm might be too large for telescope designs with central obstructions (i.e. Newtonian telescopes).

3: Exit pupils less than 0.4mm are impractical because eye floaters and eye-lashes can interfere with the view. They might also indicate the magnification is too high.

## Magnification Calculator

Calculate the magnification of a telescope and eyepiece combination. Formula: Telescope Focal Length / Eyepiece Focal Length

## Magnification/Eyepiece Calculator

Determine the eyepiece focal length required to achieve a particular magnification. Formula: Telescope Focal Length / Magnification

## Maximum Telescope Magnification Calculator

Calculate the theoretical maximum magnification possible with a particular telescope. Formula: 2.5 X Telescope Aperture (Maximum: 350x)