

JMI
AstroGear Certified
AstroGear approved with 7-day DOA protection. Includes all services from Secure Sale and shipping options.
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