Explore Scientific 3" Self-Centering Focuser - ES-FOC3

Out of stock
Regular price $1,282.00 CAD

Product details


<h3>Explore 3' Helical Rack & Pinion Focuser for Explore Refractors 120mm or Larger</h3>

With its heavy-duty build, precision dual speed focusing capability and superb lifting power, the Explore Scientific 3-inch Self-Centering Focuser is the perfect upgrade for those interested in producing beautiful astro-images.  

This heavy-duty focuser has a self-centering compression system that applies pressure equally to the draw tube, guaranteeing a tight, secure fit. This uniform pressure creates a stable base for an imaging setup and prevents flex, tilt and image shift. The draw tube, which is long enough to eliminate the need for extension tubes, is moved by a helical rack-and-pinion system lubricated with marine-grade PTFE silicone for an easy glide with maximum precision and minimal backlash. The interior of the draw tube has a diameter of 3 inches that is lined with multiple baffles to reduce reflection.

The draw tube, which has a travel of 84.5mm, is supported by a locking clutch system. The focusing system has a lifting capacity of 17 pounds. Moderate tightening offers an infinite range of tension to best suit the application.

Weighing in at 5.7 pounds, the focuser is made of black anodized aluminum. It has a 9:1 focus system with stainless-steel ball bearings and stainless-steel focus shaft. This system works as a clutch to prevent damage to the focusing mechanism. The focusing system is compatible with popular after-market electric focuser devices.

A back cell adapter with no-tool knobs attaches the focuser at four contact points to select Explore Scientific refractors with apertures ranging from 120mm to 140mm. The knobs on the adapter can be hand turned, eliminating the need for a hex key. This makes it easy to adjust the rotation of the focuser with minimal observing or imaging interruption. A Teflon ring on the focuser adds to the smooth rotation. NOTE: The Explore Scientific 152mm and 165mm models do not require this back cell adapter.

For versatility, the focuser can hold 2-inch or 3-inch visual or camera accessories and comes standard with twist-lock. In addition to allowing accessories to be secured with a compression fitting, this draw tube’s M82 x 1.25 pitch thread accepts adapters with a variety of uses.


  • Draw Tube Thread:  M82 x 1.25Draw Tube Travel:  84.5 mm/3.32 inches
  • Draw Tube Clear Interior Diameter:  76.2 mm/3 inches
  • Draw Tube Baffles: 14
  • Focus System: Helical rack & pinion
  • Reduction Ratio:  9:1
  • Attachment Mechanisms: Self-centering compression
  • Weight:  5.7 pounds
  • Compatible with electric focusers: Yes
  • Telescope compatibility:  Explore Scientific refractor telescopes 120 mm and larger; custom back cells available on request for other brands of refractor telescopes 120 mm and larger