Telescopes & Mounts

Equatorial Mount

One axis pointed at the pole, so tracking a star needs only one motor.

Specifications

Payload capacity	5 – 60 kg (imaging ≈ half the visual rating)
Tracking rates	Sidereal, lunar, solar
Periodic error	±5 to ±20 arcsec (uncorrected)
GoTo database	Typically 40,000 – 100,000 objects
Power	12 V DC, 1 – 5 A while slewing
Mount head weight	4.5 – 25 kg

Observing parameters

Polar alignment accuracy	≤ 5 arcmin for visual, ≤ 1 arcmin for guided imaging
Unguided exposure limit	30 – 120 s (depends on periodic error and focal length)
Guided exposure limit	limited by seeing, not the mount
Slew speed	2°/s to 5°/s
Image scale limit	≈ 1–2 arcsec/px before guiding is mandatory

Overview

An equatorial mount tilts its polar axis to align with Earth's rotation axis. Once that axis is aligned, the sky's daily motion becomes a single rotation about a single axis, which means one motor driven at sidereal rate keeps a target centred. It also means the field does not rotate — essential for long-exposure imaging.

The price is setup complexity. The mount must be polar aligned before tracking is useful, the telescope swings into awkward positions as it tracks, and payload weight ratings are optimistic — for imaging, aim for a mount rated at roughly double your actual payload.

Below roughly 8 kg of payload, a good alt-azimuth mount with tracking is less trouble. Above it, or for any long-exposure imaging, an equatorial mount is not optional.

Where it fits

SetupAlignmentImaging

Planet Deep sky

Practical notes

Balance in both axes with the full imaging load attached, with the tube roughly where it will be during the session.
Do a drift alignment if you plan unguided exposures longer than a minute — a polar scope alone rarely gets you under 2 arcmin.
Never loosen the clutch with the counterweights off; the tube will slam round and can bend the shaft.
For imaging, halve the manufacturer's payload figure. A mount at 100% of rating will not guide well.

Pairs with

Figures on this page are typical values for guidance only. Real performance depends on optical quality, collimation, sky brightness, atmospheric seeing and your own experience. Stargazer's Atlas sells nothing and guarantees no observing result.

Related tools

Technical line drawing of a alt-azimuth mount

Alt-Azimuth Mount Up-down and left-right, which is how you already think about the sky. Telescopes & Mountssetup

Tripod The least glamorous component and the one that most often limits the view. Telescopes & Mountssetup

Autoguider The software and interface loop that turns star drift into mount correction pulses. Imaging & Astrophotographyimaging

Guide Scope A small second telescope that watches a star so the main camera can expose for minutes. Imaging & Astrophotographyimaging