Telescope Mounting and Focuser Base Plate Choices
This focuser can be ordered with a choice of one of several base plates for your telescope (see the drop-down list above for available choices that are in stock). Please note that we are unable to recommend a specific base plate for your telescope - there is no standardization in the industry and we do not have the hole mounting specification for most scopes. You will therefore need to compare our base plate specifications with the tube/focuser specifications on your telescope and make a choice yourself. For detailed specifications and hole spacing of the available base plates, please click here.
Besides the base plate details, you must also consider the following:
(1) Make sure that the hole cut out in your telescope tube is larger than the outside diameter of the focuser drawtube. This is often an issue for telescopes smaller than 8" in aperture or for those with a smaller 1.25" focuser. However, also make sure that the current cutout is not so large that it gets in the way of the screw holes.
(2) Compare the minimum and maximum heights of the focuser (provided below) with those of your current focuser. This will indicate whether you will be able to reach focus with your eyepieces and accessories, or whether you might need extension tubes.
This GSO Dual-Speed Linear Focuser for Newtonian reflector telescopes features the most recent innovation in focuser design to hit the astronomy market in recent years. It is designed specifically to meet the heavier equipment and stability requirements of astrophotography equipment and heavy eyepieces. The linear stability and repeatable quality of focus reached with this focuser will have you returning night after night for more spectacular views, sharper images, and consistent enjoyment!
Eliminate Focuser Drawtube Slop
In conventional Crayford focusers, the drawtube is held in place by four roller bearings. Because of the small area of contact between the focuser tube and these bearings, changes in load or telescope orientation can cause some amount of slop in the focuser drawtube. The new linear bearing focuser is built with a cutting-edge rail system made of stainless steel which provides extended, consistent, and linear contact with the focusing mechanism and the inside of the focuser body, even when the focuser is fully extended. The result is zero flexure throughout the focus travel range, even in the worst case scenario when the focuser is parallel to the ground and carrying a heavy load such as a large CCD camera. This linear bearing rail mechanism also allows the use of heavier loads (GSO's rated load capacity for their linear bearing focusers is about 9 lbs (4.1 kgs)).
Smooth Focusing Action
The ultra-smooth focuser adjustment knob is only topped by the 10:1 fine adjustment knob which yields superior fine-tuning that will stay in place without slippage for hours on end. You'll feel as if the focuser is gliding on air as you meticulously seek the perfect focus. For critical imaging applications, the focuser position can be locked in place via the large thumbscrew provided for this purpose on the top of the focuser. The focusing tension can be controlled by another large screw on the underside of the focuser. The drawtube features a laser-etched measurement scale for quick and repeatable focusing.
Very High Quality Construction and Features
The highly polished, anodized black aluminum is complemented by the meticulous CNC machining. Every part is carefully selected and designed to deliver a linear focusing system that will provide both beauty and quality for years to come. The 2" focuser barrel features a brass compression ring. Also included is a 2"-1.25" adapter with brass compression rings and threads to accept standard 2" filters. The focus travel is a generous 2".
Specifications (With Curved Base Plate)
• Minimum focuser height (without 1.25" adapter) = 3.05" (77.5mm)
• Maximum focuser height (without 1.25" adapter) = 5.05" (128mm)
• 2"-1.25" adapter height = 0.39" (10mm)
• Tube travel = 2" (50.8mm)
• Drawtube outside diameter (cut-out in your telescope tube must exceed this) = 2.32" (59mm)
• Steel rail width = 0.56" (14.1mm)
• Focuser weight (with 1.25" adapter) = 1lb-11.5oz (779gm)
• Focus knob diameter = 1.57" (40mm)
• Microfocus knob diameter = 1.06" (27mm)
• Maximum outer body diameter = 3.23" (82mm)
• Measurement scale on focuser drawtube: Yes
• Rotatable: No (But body can be rotated by loosening two allen screws that connect the focuser to the base plate)
• Dust plug: One 1.25" dust plug included
• The focuser is shipped in a foam-fitted padded box.
• No instruction manual is included.