Heli-FOK

The Heli-FOK is a 2" Helical-Crayford focusser with a very short design, ideal suited for fast telescopes or if you are aiming for a secondary mirror with minimal diameter.

Since it´s introduction at the ATT fair of 2000 the Heli-FOK is used by lot´s of customers with great enthusiasm. The Heli-FOK is a high-quality and low-priced 2" focusser. It´s the ideal choice for any large Dobsonian or as a replacment for those focussers of minor quality often found on commercial telescopes today.

Construction-details:

• Modified Crayford design: Free of backlash and extremely viable by principle
• Convenient, fast and precise focus by rotating the eyepiece
• minimum optical length and height of 40mm only
• Large adjustment range of 27mm
• The drawtube is secured against accidental unscrewing
• In fully retracted the drawtube protrudes approx 26mm inside out over the front edge
• All components made of black anodized aluminum, stainless steel or Teflon. Thumbscrews with plastic heads
• The drawtube is pressed by two set screws with teflon base on four ball bearings. Additional, you may clamp the drawtube in each Positon with a third screw securely.

The focusser can handle large loads, such as (DSLR-)cameras, CCD cameras or heavy 2 "eyepieces.
However, the Heli-FOK is not perfectly suited for the use of cameras, CCD cameras or Binocular-viewers, as they would have to be rotated for focusing.




Technical Data:
The outer body has a diameterof 80mm.
Three M5 threads to mount the focusser to the telescope. (120°, radius 42mm)
Minimum height: 40mm
Maximum height 67mm
Weight 330g

Citation from one of my customers:
(Martin Neuer) "... I have two of Gerd's Heli-Fok focussers in use and they can be highly recommend. (...) The Heli-Fok are  solid, clearly adjustable, and really good. Compared to other focussers they´re quite inexpensive ... "