TS-Optics 2" MONORAIL Dual Speed Focuser for SC Telescopes - SC Thread

This focuser is more stable and more accurate than usual Crayford focusers. We recommend the focuser especially for astrophotography.

♦ Telescope connection: 2" SC thread

♦ Eyepiece side connection: 2" and 1.25" receptacle with compression ring

♦ Minimal height to thread: 112 mm

♦ Draw tube travel: 50 mm

♦ Dual speed 1:10 for accurate focusing

♦ Bearing via stainless steel rail - absolutely free from twisting

♦ Central locking of the draw tube, guaranteed without tilting


 

TS-Optics 2" MONORAIL with 2" SC Thread

The TS monorail focuser for many Schmidt-Cassegrain telescopes from Celestron and Meade as well as Maksutov-Cassegrains from Intes 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 MonorailSC has a 2" SC thread on the telescope side. This allows the connection to SC telescopes from Celestron and Meade, but also to Maksutov Cassegrains from Intes and some RC telescopes.

With this focuser you can not only focus very precisely, but also avoid the annoying mirror shifting.

Attention: For most fork mounted SCs the focuser is too long, so it would hit the base, and for telescopes below 6" aperture the focus knob is too close to the thread to allow the focuser to be mounted.
 

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 left.

Telescope connection:	2" SC thread
Eyepiece side connection:	2" receptacle with compression ring and reduction adapter to 1.25"
Minimum height SC thread to 2" receptacle:	112 mm
Draw tube travel:	50 mm
Scale:	mmm and inch
Dual speed:	included
Bearing:	Stainless steel rail - Monorail principle
Weight:	860 g incl. 1.25" reduction adapter
Body outer diameter:	84 mm

♦ 2" Monorail focuser with 2" SC thread
♦ Reduction adapter from 2" to 1.25"