harwayharry
26-01-2008, 01:11 AM
Aluminium anodised in black, this is a great focuser for building your own scope or a perfect upgrade for a scope that uses a 2" focuser. It includes a 1Ό" adapter.
This focuser came with my 12" Lightbridge and I have now upgraded to a 2 speed model. It suits 10" - 12" scopes. It fits (at least) Meade, GSO & Bintel scopes. Given the unkind weather late last year, this has only been used on two club Deep Sky weekends.
$55 + registered post at cost. If you would like to check estimated postage costs with the Australia Post on-line calculator, the parcel is 17cm x 13cm x 13cm and will come from Mawson ACT 2607. Pickup in Canberra AOK
Background to the Crayford:
John (Jack) Wall in England invented the Crayford Eyepiece Mount (CEM) or Crayford focuser. The name Crayford comes from the Crayford Manor House Astronomical Society (UK) to which he belongs.
The Crayford design moves the focuser drawtube by applying high pressure on a metal drive shaft that in turn presses against a flat surface machined into the metal focuser drawtube. The drawtube is held in place by sets of bearings on the opposite side of the drawtube from the drive shaft. This direct metal-to-metal and surface-to-surface drive mechanism eliminates the problems found in the rack-and-pinion focusers found on many telescopes, such as backlash, gear slop, and side to side shifting of the drawtube as the focus knob is turned.
The Crayford design allows for very fine adjustments, with tolerances up to 100 times better than conventional rack-and-pinion focusers. Its zero image shift and zero backlash makes it outstanding for visual and photographic work and a must for CCD imaging.
This focuser came with my 12" Lightbridge and I have now upgraded to a 2 speed model. It suits 10" - 12" scopes. It fits (at least) Meade, GSO & Bintel scopes. Given the unkind weather late last year, this has only been used on two club Deep Sky weekends.
$55 + registered post at cost. If you would like to check estimated postage costs with the Australia Post on-line calculator, the parcel is 17cm x 13cm x 13cm and will come from Mawson ACT 2607. Pickup in Canberra AOK
Background to the Crayford:
John (Jack) Wall in England invented the Crayford Eyepiece Mount (CEM) or Crayford focuser. The name Crayford comes from the Crayford Manor House Astronomical Society (UK) to which he belongs.
The Crayford design moves the focuser drawtube by applying high pressure on a metal drive shaft that in turn presses against a flat surface machined into the metal focuser drawtube. The drawtube is held in place by sets of bearings on the opposite side of the drawtube from the drive shaft. This direct metal-to-metal and surface-to-surface drive mechanism eliminates the problems found in the rack-and-pinion focusers found on many telescopes, such as backlash, gear slop, and side to side shifting of the drawtube as the focus knob is turned.
The Crayford design allows for very fine adjustments, with tolerances up to 100 times better than conventional rack-and-pinion focusers. Its zero image shift and zero backlash makes it outstanding for visual and photographic work and a must for CCD imaging.