The TS Monorail focuser for many refractors from Skywatcher, Celestron and Orion is an improvement of the time-tested Crayford focusers. Our goal was to offer a focuser for highest loads, like heavy CCD cameras, with very high precision at the same time. We exactly succeeded in this with the Monorail focusers.

The MonorailR86 has an 86 mm connecting flange on the telescope side with three M4 internal threads. This allows the connection to Skywatcher, Celestron and Orion refractors with 90 mm tubes, as they are often used with 80 mm and 90 mm aperture.

The advantages of the TS Monorail focusers at a glance:

• higher load capacity than with normal Crayford focusers - instead of small ball bearings, a massive stainless steel rail, which is laterally clamped, is used.
• more precise guiding of the draw tube and no more tilting when locking
• smooth motion and finest adjustment even at loads of up to 4 kg
• 1:10 dual speed for accurate focusing
• Motor focus can be retrofitted

Operating principle of the Monorail focuser and the advantage compared with Crayford focusers:

Instead of small ball bearings, like in Crayford focusers, a massive stainless steel rail handles bearing and also lateral fixing.

The disadvantage of Crayford focusers with ball bearings: The small ball bearings of the Crayford focuser are loaded if locked. As the locking screw is not placed exactly between the ball bearings, one pair of the bearings is more heavily loaded. This results in tilting and unsharp stars in one corner.

The advantage of the MONORAIL principle: The function of the ball bearings is taken over by the stainless steel bar which is firmly connected to the draw tube. Nothing can bend anymore. Only lateral guidance is taken over by ball bearings. These bearings only fix the lateral position and do not need to take on load anymore.

The drawtube is fixed with a locking screw which is exactly centered at the upper side, so the entire construction is evenly loaded. Tilting is definitively avoided, the draw tube stays exactly at the given position.

With the middle screw of the "quincunx", only the friction is adjusted - see image at top.