Eyepiece and telescope pairing

Tele Vue 32mm Plossl in the Sky-Watcher Heritage 130P: magnification and field

What the Tele Vue 32mm Plossl does in the Sky-Watcher Heritage 130P, worked from the published focal lengths and apparent field.

Field of view

ring = 2.46 degrees true
dot = 6.4 mm exit pupil

Computed optics

Magnification
20x650 mm / 32 mm
True field
2.46 degrees50 deg / 20x
Exit pupil
6.4 mm130 mm / 20x
Max useful mag
about 260x2x aperture
Barrel match
1.25 in eyepiece in a 1.25 in focuser
Fits

Good fit. In the Sky-Watcher Heritage 130P the Tele Vue 32mm Plossl gives 20x with a 2.46 degree true field and a 6.4 mm exit pupil, inside the telescope's useful range.


Magnification is the telescope focal length divided by the eyepiece focal length: 650 mm divided by 32 mm is 20x. The true field of view is the eyepiece's 50 degree apparent field divided by that magnification, 2.46 degrees.

The exit pupil, the width of the light beam leaving the eyepiece, is the aperture divided by the magnification, 130 mm over 20x, which is 6.4 mm. That makes this a low-power, wide-field and deep-sky setting.