Limiting Magnitude introduction

This is the magnitude (or brightness) of the faintest star that can be seen with a telescope. The larger the number, the fainter the star that can be seen. An approximate formula for determining the visual limiting magnitude of a telescope is                                            9 + 5 log aperture (in inch).

This is the formula that we use with all of the telescopes we carry, so that our published specs will be consistent from aperture to aperture, from manufacturer to manufacturer.
 Some telescope makers may use other unspecified methods to determine the limiting magnitude, so their published figures may differ from ours.

Limiting Magnitude Calculator(click)