Monorail 2" dual speed Focuser - higher load capacity and smoother movement than our Crayford types
... the monorail system is an improved variant of the Crayford design principle with better performance. With M90x1 thread e.g. for GSO / Astrotec RC systems



The TS Monorail focusers are improvements of the time-tested Crayford focuser design. Our goal was to increase the load capacity of the focuser and at the same time offer an even smoother focusing motion and better focusing precision. The Monorail focusers meet all those goals! This model fits directly to the 6 + 8" Ritchey-Chrétien telescopes by GSO and Astrotech

Advantages of the TS Monorail focusers:

-- Higher load capacity. Instead of using roller bearings on the opposite side of the focuser drawtube the bearings are
   located on the focuser's steel rail. This allows for more focuser friction without bending the focuser drawtube out of
   shape.
-- Precisely aligned focusing drawtube. No tilting out of alignment when tightening the locking screw.
-- Smooth focusing motion even under heavy loads up to 4kgs
-- 1:10 dual speed microfocuser for fine focusing

Operating principle of the monorail focusers:



How a standard Crayford focuser works:

The focuser drawtube is pressed against four roller bearings at the opposite side of the focusing spindle. In order to keep the diameter of the focuser as small as possible usually very small roller bearings are used. Unfortunately this means that the roller bearings have very thin walls and can therefore be deformed by the pressure. An additional problem is that the drawtube itself might be bent out of shape. On the TS Crayford focusers we use relatively large roller bearings to counter-act this effect as much as possible.

The locking screw of most Crayford focusers is not centered between the four roller bearings, but instead is located slightly excentrically. When tightening the locking screw the drawtube can be moved out of alignment by a small degree. This is not noticeable visually or with light photographical loads, but when tightening the screw firmly for heavy photographical loads this can result in deteriorating image sharpness towards one edge of the photographical field.

How the TS Monorail focuser works:

The focusing spindle and the ball bearings operate on the same steel rail that is fixed on one side of the focuser's drawtube. Instead of thin-walled roller bearings a straight ball bearing is used that runs in parallel to the steel rail. Through this design trick it is possible to use more friction without bending the bearing out of shape. The drawtube itself no longer needs to withstand the pressure.

With the thumbscrew between the focusing knobs you can finely adjust the tension and thus the load capacity.

The locking screw is positioned precisely in the center of the bearing, on the opposite side of the drawtube. Tightening the screw will not move the drawtube out of alignment.

Technical details:
-- 2" Monorail focuser with brass compression ring and 2"/1.25" reducer
-- Mount thread: M90x1 Anschlussgewinde
-- Drawtub travel: 50mm
-- Scale: inch + metric
-- Weight: 860g incl. 1.25" reducer

Scope of deliver:
-- TS 2" Monorail focuser with female M90x1 thread on telescope side
-- Brass compression ring with two thumbscrews for 2" accessories
-- 2" / 1.25" redcuser with brass compression ring