CARBON FIBRE TUBE: Carbon fibre is a strong and lightweight material and has much better thermal stability compared to a steel tube. This is especially important for astro-photographers dealing with long exposure times. Imaging telescopes made of less thermally stable material can deviate from optimum focus after long time exposures. With a carbon fibre tube, it can remain in focus for a longer period of time and long exposure images will stay clear and in focus.   Tube interiors are equipped with knife-edge ray traced baffles.  

2" DUAL-SPEED LINEAR POWER FOCUSER: The new linear power focuser utilizes 4 precision ball bearings to support the draw-tube and provide great stability and zero image shift while supporting a heavy eyepiece or camera. Moving the draw-tube by the roller rather than a rack and pinion ensures exceptionally smooth operation, great feel and precise adjustability. The dual-speed feature has a second focus knob that has a 10:1 speed reduction to provide the super-fine adjustments even the most demanding users can appreciate.

PYREX MIRRORS: Both models feature paraboloidal primary mirrors made of low thermal expansion Pyrex glass resulting in substantially shorter cooling-down times.

Specifications

Optical Design                        Reflector

Diameter                               254F

ocal Length                            1000mm

F/Ratio                                   f/4

Highest Practical Power           508x

Finder Scope                          9 x 50

Focuser Diameter                   2" (50.8mm)

Dual-Speed                            10:1 Linear Power Focuser

Sky Watcher Quattro 250 CF Astro Photography Reflector