Sky-Watcher Skymax 102: 102 mm aperture, 1300 mm focal length, f/12.7, Maksutov-Cassegrain. The magnification, true field and exit pupil each eyepiece gives, and the barrel, mount and camera adapter that fit.

Updated 05 September 2026.

Optical reference

Sky-Watcher Skymax 102: aperture, focal length and eyepiece fit

What the Sky-Watcher Skymax 102 measures, the magnification and true field each eyepiece produces in it, and the barrel, mount payload and camera adapter that fit.

Published specifications

Aperture
102 mm (4.02 in)
Focal length
1300 mm
Focal ratio
f/12.7
Optical design
Maksutov-Cassegrain
Focuser / eyepiece barrel
1.25 in visual back; rear thread accepts a 1.25 in or 2 in back
Mount
Optical tube (V-style dovetail), sold as OTA or on a GoTo mount
Highest useful magnification (2x aperture rule)
about 204x

Eyepiece ladder

2 pairings

The Skymax 102 is a 102 mm Maksutov with a long 1300 mm f/12.7 focal length in a compact sealed tube. It is a lunar and planetary specialist, and low power is capped by the focal length rather than the eyepiece.

Because magnification is the telescope's 1300 mm focal length divided by the eyepiece focal length, a 25 mm eyepiece gives 52x here and a 10 mm eyepiece gives 130x. The highest useful magnification is about 204x (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

Questions and answers

What is the aperture of the Sky-Watcher Skymax 102?

102 mm (4.02 in)

What is the focal length of the Sky-Watcher Skymax 102?

1300 mm

What is the focal ratio of the Sky-Watcher Skymax 102?

f/12.7

What is the optical design of the Sky-Watcher Skymax 102?

Maksutov-Cassegrain