Sky-Watcher Quattro 250p
The new QUATTRO series with their fast f/4 focal ratios, have been specially designed for high quality astrophotography with short exposure times. They are of course also fine telescopes for visual observations. Tube interiors have knife-edge ray-traced baffles.
250mm f/4 Dual-Speed Parabolic Imaging Newtonians
2" DUAL-SPEED LINEAR POWER FOCUSER (both models): The new linear power focuser utilises 4 precision ball bearings to support the drawtube and provide great stability and zero image shift while supporting a heavy eyepiece or camera. Moving the drawtube 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 parabolic primary mirrors made of low thermal expansion Pyrex glass resulting in substantially shorter cooling-down times.
- Highest Practical Power (Potential) x508
- Diameter of Primary Mirror 254mm
- Telescope Focal Length 1000mm (f/4)
- Note: Eyepieces NOT supplied
- 9x50 Finderscope
- Parabolic Primary Mirror (Pyrex)
- 2" (50.8mm) Dual-Speed 10:1 Linear Power Focuser
- Tube Rings and Dovetail Bar
- 0.5mm Ultra-Thin Secondary Mirror Supports
- 56% more Light-Gathering than 200mm
Quattro-10S (steel tube)
Product code – 10239
10” f/4 Newtonian OTA designed for wide-field imaging. This uses a parabolic primary mirror so at f/4 there will be a noticeable amount of off-axis coma. Use the Baader or Skywatcher coma corrector for images free of coma. These telescopes can also be used visually, but bear in mind that as they are optimised for wide-field imaging, the secondary will be a little larger to reduce vignetting. Its performance visually will likely be slightly inferior to a standard f/5 visual Newtonian. With the coma corrector these instruments are capable of excellent photographic results. The carbon fibre tube assembly is designed so that there is no linear movement of the tube length or width as it cools. It does not expand or contract during temperature change like metals. This means that during a long exposure, the image on the chip will remain in sharp focus. Bear in mind that carbon fibre does not lose heat very quickly, so although the tube will not move, it will radiate for longer than aluminium or thin ferrous metal. A carbon fibre tube needs to be left to cool for longer, prior to serious imaging.
Budget for a good quality coma corrector – essential. Preferably, one that does not alter the focal length of the telescope. Construct a matt black dewshield of some 300mm in length. This will help to draw cool air up through the telescope passively, and also decrease light reflections around the secondary position. Keep these telescopes in perfect collimation. Even slight mis-alignment in an f/4 Newtonian noticeably reduces image quality.
- Optical Design
- 10 inch
- Focal Length
- 1000 mm
- Focal Ratio