Will My Rig Fit? Pier Sizing & Swing-Diameter Guide
What “swing diameter” means: the maximum circular clearance your telescope and accessories need as the mount slews past the meridian and horizon. Choose a pier with a swing diameter greater than your rig’s full width including dew shields and cables.
Mount Sizing Reference
Measuring Swing Diameter
Hover or tap the red lines to see each measured distance from the RA pivot. The longer of the two is your Swing Radius — double it for the Swing Diameter your mount and pier need to clear.
Legend
① RA Pivot — rotation center
② Pivot → Counterweight end
62 cm
③ Pivot → Objective end
85 cm
Measure from the RA Pivot (yellow point) to the most distant points on the telescope — the red lines. The longer of these is your Swing Radius. Double it for the Swing Diameter.
Live Calculation
Longer distance (Swing Radius)
85 cm
Swing Diameter
170 cm
How to measure (steps):
- Assemble your full imaging train.
- Extend dew shield/focusers as in use.
- Measure the widest span perpendicular to the tube’s length (include dovetail/saddle).
- Add 5–10 cm of safety margin.
Tip: long refractors often need more diameter clearance than their weight suggests.
Payload & mounts:
- Compact (≤ 4 kg): smart scopes.
- Small (≤ 8 kg): AM3/HEQ5 class with 60–80 mm APO or 5″ SCT.
- Standard (≤ 20 kg): EQ6-R/AM5 class with 100–120 mm APO or 8″–10″ SCT/RASA 8.
- Heavy (≤ 45 kg): premium mounts (Paramount MX, GM2000, etc.) with 10″–12″ RC/Newt or duals.
Checklist before you book:
- Swing diameter ≥ your measured clearance (+ safety margin).
- Payload within tier limit (include cameras, filter wheels, OAG, cables).
- Balance achievable in both axes; cable management planned.
- Power/network ports sufficient (see Add-ons for extras).
See examples: