GSO 2" Linear Bearing Crayford Focuser for Reflectors - Dual Speed

Our #: PAF-GS-M-LRN-BUNDLE
Mfg #: -

Our Price: $190.00

Free shipping for this item in the US
More Info

Contiguous US Customers:
All items we sell ship for free within the Contiguous US. Shipping will be via the cheapest shipping method which will vary depending on the items in your order. During checkout, you may also be shown other optional faster shipping choices.

US Customers in Hawaii and Alaska:
Free shipping applies to almost all products. A few large telescopes and mounts are excluded from this free shipping offer. For these items, please contact us to obtain a shipping quote before you check out using the online shopping cart.

International Customers:
Free shipping does not apply to international orders. During check-out, you will be presented with several shipping choices and costs. However, the export of some items may be restricted outside the US due to size or manufacturer restrictions.

Out of Stock
Availability: Expected mid-April

Product Details

1. Selecting the Right Reflector Focuser for your Newtonian or Dobsonian Telescope:

GSO 2" reflector Crayford focusers are available in 4 versions:

  1. Single speed Crayford focuser # GS-CRF (sold separately):
    Suitable for visual applications. Cannot be used with ZWO EAF.
  2. Dual speed Crayford focuser # GS-M-CRF (sold separately):
    Suitable for visual applications with fine focus control or for light imaging payloads. Not compatible with the ZWO EAF out of the box but can be adapted with 3rd party 3d-printed brackets.
  3. Dual speed linear bearing focuser # GS-M-LRN (this item):
    Suitable for visual applications with fine focus control for heavier eyepieces or for heavier imaging applications. Not compatible with the ZWO EAF out of the box but can be adapted with 3rd party 3d-printed brackets.
  4. Dual speed ZWO EAF-compatible linear bearing focuser # GS-M-LRN-D (sold separately):
    Suitable for visual applications with fine focus control for heavier eyepieces or for heavier imaging applications. Compatible with the ZWO EAF out of the box without the need for other 3rd party brackets.

2. 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 the many scopes on the market. 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 is not something we will be able to specify for your specific telescope or eyepiece collection.

3. Description:

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!

A. 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)).

B. 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.

C. 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 50mm (almost 2").

4. Specifications (With Curved Base Plate)

• Minimum focuser height (without 1.25" adapter) = 3.09" (78.6mm). Note that in this position, the inner drawtube extends below the curved base plate by about 32mm which may intrude into your scope's light path.
• Maximum focuser height (without 1.25" adapter) = 5.06" (128.6mm)
• 2"-1.25" adapter height = 0.39" (10mm)
• Tube travel = 1.97" (50mm)
• 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

5. Additional Comments:

• No mounting screws are included with the base plate. You will need to provide your own.
• The focuser is shipped in a foam-fitted padded box.
• No instruction manual is included.

Other Information

  • Country of Manufacture: Taiwan
Copyright Notice: This description was developed by Agena Astro. It was NOT provided by the supplier/manufacturer of this product. Please do not copy for personal or commercial use.