Optical reference

Sky-Watcher Skymax 127: aperture, focal length and eyepiece fit

What the Sky-Watcher Skymax 127 measures, the magnification and true field each eyepiece produces in it, and the barrel, mount payload and camera adapter that fit.

Published specifications

Aperture
127 mm (5 in)
Focal length
1540 mm
Focal ratio
f/12.1
Optical design
Maksutov-Cassegrain
Focuser / eyepiece barrel
supplied with a 2 in diagonal and a 1.25 in adapter; rear thread accepts 1.25 in or 2 in visual backs
Mount
Optical tube (V-style dovetail), sold as OTA or on the AZ-GTi
Highest useful magnification (2x aperture rule)
about 254x

Eyepiece ladder

2 pairings

The Skymax 127 is a 127 mm Maksutov with a long 1540 mm f/12.1 focal length in a short, sealed tube. It is a planetary and lunar specialist, and its narrow field means low-power views are limited by the focal length rather than the eyepiece.

Because magnification is the telescope's 1540 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 62x here and a 10 mm eyepiece gives 154x. The highest useful magnification is about 254x (roughly twice the aperture in millimetres), beyond which the image dims and softens without showing more detail.

The focuser takes 2 in eyepieces, so long 2 in wide-field eyepieces such as the Omni 56 mm fit as well as 1.25 in ones.

Match an eyepiece, mount or camera