Built for serious astrophotographers, the Explore Scientific 3-inch Self-Centering Focuser is engineered to provide unwavering support, zero image shift, and precise focusing control, even with the heaviest imaging equipment. Designed for large refractors, it incorporates a self-centering compression system that applies equal pressure around the 3-inch draw tube, ensuring perfectly aligned, tilt-free performance.
Its helical rack-and-pinion drive, lubricated with marine-grade PTFE silicone, delivers smooth, backlash-free movement, while the dual-speed 9:1 focusing system ensures ultra-fine control over your imaging or visual sessions. The draw tube extends 84.5 mm, features 14 internal baffles for glare suppression, and includes M82 x 1.25 pitch threading for wide accessory compatibility.
A tool-free back cell adapter enables quick attachment and smooth 360° rotation using hand knobs, eliminating the need for hex wrenches. The twist-lock compression rings support both 2" and 3" accessories, and the entire unit is electric focuser–ready for full automation flexibility.
Compatibility Notes:
• White-tube Explore Scientific refractors with threaded back cells must be shipped to Explore Scientific for adapter installation. Contact customer service to arrange.
• The FPL53-165CF telescope requires a separate back cell adapter.
• The TED15208CF telescope does not require an adapter—this focuser fits directly.
CA Residents: Prop 65 WARNING(S)
🌟 Who It’s For
- Astrophotographers needing reliable support for heavy imaging setups
- Visual observers wanting micro-level focusing precision on large refractors
- Telescope users upgrading from stock focusers for better mechanical performance
- Owners of Explore Scientific 120mm–140mm refractors (or others with adapter support)
🎯 What You’ll Be Able to Do
- Achieve tack-sharp focus in high-resolution astro images
- Eliminate flex, backlash, and sag in imaging trains
- Rotate your focuser setup easily during visual or imaging sessions
- Fine-tune focus for both planetary and deep-sky astrophotography
🎒 What’s Included
- Explore Scientific 3" Self-Centering Focuser (black anodized aluminum)
- Tool-free back cell adapter for Explore Scientific refractors (120mm–140mm)
- 2" and 3" twist-lock compression rings
- Pre-installed stainless steel rack, pinion, and ball bearing system
- Integrated 14-baffle draw tube
- M82 x 1.25 pitch threading
- User documentation
Specs
| Item Number | ES-FOC3 |
|---|---|
| Lifting Capacity | 17 lbs (7.7 kg) |
| Draw Tube Travel | 84.5 mm (3.32 in) |
| Draw Tube Clear Interior Diameter | 76.2 mm (3 in) |
| Draw Tube Thread | M82 x 1.25 |
| Draw Tube Baffles | 14 |
| Focus System | Helical rack & pinion |
| Reduction Ratio | 9:1 with stainless steel ball bearings and shaft |
| Attachment Mechanism | Self-centering compression |
| Weight | 5.7 lbs (with 3" to 2" twist-lock adapter) |
| Compatible with Electric Focusers | Yes |
| Telescope Compatibility | Explore Scientific refractors 120 mm and larger; custom adapters available for other brands |
Warranty Information:
This product is covered by a Limited One-Year USA Warranty, valid when registered within 60 days of purchase. To activate your warranty, please visit the Explore Scientific website and complete the registration form at: