JMI Event Horizon Crayford Focuser for SCTs (EAF-ready)

JMI Event Horizon EV-SCT Dual-Speed Crayford Focuser

Premium dual-speed Crayford focuser designed for Schmidt-Cassegrain telescopes. Offers exceptionally smooth, precise focusing with zero image shift — ideal for both planetary and deep-sky imaging. This particular unit has been professionally drilled and tapped to mount an Electronic Automatic Focuser (EAF), providing seamless motorized control for astrophotography.

Specifications

• Model: JMI Event Horizon EV-SCT

• Type: 2″ dual-speed Crayford focuser (manual fine/coarse adjustment)

• Drawtube Travel: ~15 mm smooth linear motion

• Fine Focus Ratio: 10:1 reduction

• Attachment: Standard SCT rear thread (fits Celestron, Meade, etc.)

• Load Capacity: Supports imaging trains up to ~3 kg (camera, filter wheel, reducer, etc.)

• Body Construction: CNC-machined aluminum with anodized finish and Teflon-lined bearings for zero-backlash motion

• Optical Path Length: Adds ~60 mm to the imaging train

• Modification: Rear housing drilled and tapped post-manufacture to securely mount a ZWO EAF (or compatible motor) — maintains perfect alignment and smooth motion

• Drive Type: True Crayford friction-drive mechanism — no image shift

• Rotation: 360° rotatable body with brass compression ring for secure eyepiece or camera clamping

• Compatibility: Designed for Schmidt-Cassegrain telescopes (C6–C11); not suitable for refractors or Newtonians without an adapter

• Condition: Excellent — smooth travel, firm tension adjustment, clean threads, minimal cosmetic wear

• Use Case: High-precision manual or motorized focusing for astrophotography

• Origin: Manufactured by JMI (Jim’s Mobile Instruments), USA