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Product Selection - Newtonians 2.0 Draw Tube Travel

We've identified the major telescope types, and listed which draw tube lengths have been known to work for scopes of that type. We are currently working to compile a more exhaustive reference resource to help match the right equipment to various applications.

Before purchasing your focuser, however, you should make sure that the focuser you select will have room for your particular set up. As always, if you have any questions, or need help in selecting the right product, please don't hesitate to contact us.

Starlight Instruments Basic Product Selection Matrix 01.01.09
Newtonian Schmidt-Cassegrain Refractor 2" Refractor 3" Micro
*1.5" *2.0" *2.5" *0.8" *1.5" *1.5" *2.0" *2.5" *3.5" For Tak For Tele Vue
What model do I need?
Automated Systems
Motorized Feather Touch System
* Note: measurement represents length of draw tube travel, in inches

Newtonians - 2.0" draw tube travel

Note: Base plate(s) and eyepiece adapter(s) sold separately.

2.0'' Diameter - Low Profile 2.0'' Travel
Model F2020DScr Model F2020DSCRcr
Focusers Focusers
Base Model
   
Model F2020DSBcr Model F2020DSBCRcr
Focusers Focusers

Standard Features

  • Ultra-smooth coarse/fine focus knobs (10:1 Ratio approximate)
  • Durable hardened stainless steel, steel, and aluminum construction
  • Standard Draw Tube with nylon-tipped stainless steel set screws (gentle on eyepieces)
  • 52mm threaded Draw Tube to accommodate filters
  • Glare resistant black internal baffling
  • Anodized aluminum fine focus knob
  • Ultra-Low backlash system for accurate control
  • Sleek aesthetic design

Base Plates for Newtonians (Dobsonians) (2.75 Square Bolt Pattern)

Standard Flat Base
Standard Flat Leveling Base
Custom Machined Curved Base (Outside Tube Diameter Required)
Custom Machined Curved Leveling Base (Outside Tube Diameter Required)

Eyepiece Adapters (1.25" to 2.00" Adapter with 48mm threads for filters)

Original Low Profile  (sits flush with draw tube, adds “0” length.)
Easy Grip  (with raised knurled edge for easy gripping adds “0” length)
Standard  (standard refractor style adapter, adds 7/16 in back focus)

Features and Equipment Details

Draw Tube Compression Ring - Back to Top

Focusers
Photo Featuring Brass Compression Ring

We have recently introduced a new design that incorporates a brass compression ring. This ring acts as a buffer between the thumb screws and your eyepieces so that it will not mar them. The Compression Ring also has improved holding power over the nylon tipped screws.

NOTE: There are two thumb screws on our draw tubes with the Compression Ring. The right screw is used for 2” eyepieces and the left screw is used for 1 ¼ eyepieces.
The left thumb screw is nylon tipped and can also be used in addition to the right thumb screw. When used with our 1 ¼ -2 inch zero length adapter, the left thumb screw is used to hold the 1 ¼ eyepiece in place.

NOTE:

  1. All draw tubes are machined with internal anti-reflection baffling.
  2. All draw tubes also have a 52 mm thread machined on the back surface. This will accommodate permanent or semi permanent filters if desired, such as Light Pollution Filters, clear filters for dust protection, etc. Step down adapters that reduce the 52 mm thread to 48 mm threads are available through larger camera stores. 

Internal Brake System (IBS) - Back to Top

In some Newtonian telescopes the brake option may be needed. If the draw tube motion is not horizontal and has a vertical component, the brake option should be considered. This may be needed if heavy eyepieces or accessories are used that may result in the draw tube to drift from its set position. This is necessary because our focusers are so smooth and move so freely. Although they will hold some weight in the vertical position without drifting (generally about 1 lb.), if more control is needed the IBS should be considered.

The brake consists of a lever arrangement internal to the pinion block. By adjusting the thumb screw on the pinion block this lever presses a friction pad onto the pinion thereby increasing the torque that is needed to turn the focus knobs. If the thumb screw is turned all the way in, the pinion shaft and the draw tube will be locked. Opposite this thumb screw is a small set screw that is factory set and should not be adjusted by the customer.

Standard Flat Base - Back to Base Plates List

Focusers
Model 2015 shown with Brake, Compression Ring, and Standard Flat Base

Generally a flat base can be used for most Newtonian applications if the optics are in proper alignment and if the upper cage or telescope tube has a flat mounting surface. If adjustments are necessary the focuser base can be shimmed underneath the base.

Although this method may be a bit more time consuming, it is less likely to change over time especially when wooden or cardboard tubes are used. Mounting hardware is supplied with  each focuser base. A 2 5/8 - 2 ¾  inch diameter hole is required for the draw tube clearance while the base itself uses a 2 ¾ inch square bolt hole pattern.  The screws used to attach the focuser base to the tube are 8-32 Socket Head Cap Screws (Allen Heads). 

NOTE: A 2 5/8 - 2 3/4 inch diameter hole is required for the draw tube clearance and the bases uses a 2 ¾ inch square bolt hole pattern. The screws used to attach the focuser base to the tube are 8-32 Socket Head Cap Screws (Allen Heads).

Standard Flat Leveling Base - Back to Base Plates List

Focusers
Model 2015 shown with Brake, Compression Ring, and Standard Flat Leveling Base

The flat leveling base uses four brass leveling screws to assist in the adjustment and collimation of the focuser. The screws have a specially designed domed face so that they contact more of the wood or cardboard surface to prevent seating of the screws. The focuser will have to be loosened and rotated to make this adjustment using the two set screws on the base.

NOTE: A 2 5/8 - 2 3/4 inch diameter hole is required for the draw tube clearance and the bases uses a 2 ¾ inch square bolt hole pattern. The screws used to attach the focuser base to the tube are 8-32 Socket Head Cap Screws (Allen Heads).

Custom Machined Curved Base - Back to Base Plates List

Focusers
Model 2015 featuring Curved Base, Compression Ring, and Original Low Profile Adapter

A curved base can be custom machined to match your tube diameter if it does not have a flat mounting surface. 

NOTE:

  1. A 2 5/8 - 2 3/4 inch diameter hole is required for the draw tube clearance and the bases uses a 2 ¾ inch square bolt hole pattern.  The screws used to attach the focuser base to the tube are 8-32 Socket Head Cap Screws (Allen Heads).
  2. *** When ordering, you must supply us with the outside tube diameter of your scope. For custom radius bases please measure the tube diameter across two perpendicular distances through the centerline of the tube and average these two values.
  3. Mounting hardware is included with the base.

Custom Machined Curved Leveling Base - Back to Base Plates List

Focusers
Model 2015 shown with Curved Base and Compression Ring

The curved leveling base uses four brass leveling screws to assist in the adjustment and collimation of the focuser. The leveling screws are drilled at an angle for improved contact between the screw face and the tube. The focuser will have to be loosened and rotated to make this adjustment using the two set screws on the base. 

NOTE:

  1. A 2 5/8 - 2 3/4 inch diameter hole is required for the draw tube clearance and the bases uses a 2 ¾ inch square bolt hole pattern.  The screws used to attach the focuser base to the tube are 8-32 Socket Head Cap Screws (Allen Heads).
  2. *** When ordering, you must supply us with the outside tube diameter of your scope. For custom radius bases please measure the tube diameter across two perpendicular distances through the centerline of the tube and average these two values.
  3. Mounting hardware is included with the base.

Original Low Profile Adapter - Back to Eyepiece Adapters List

Focusers

Our Low Profile adapter is designed to add zero length when inserted into the 2 inch draw tube.

The thumb screws on the draw tube can be used for holding the 1 ¼ adapter and the eyepieces simultaneously. This adapter has no flange and works well with larger eyepieces.

  • All 1 ¼ eyepiece adapters are interchangeable with our focuser draw tubes and come with a brass compressing ring.
  • All 1 ¼ eyepiece adapters have a 48 mm thread machined in the back to accommodate 2 inch filters.

Easy Grip Adapter - Back to Eyepiece Adapters List

Focusers

Our Easy Grip Adapter is the same as our Original Low Profile Adapter but with an additional raised flange that adds ¼ of an inch. For most eyepieces this flange does not interfere and allows gripping the adapter for easier removal.

  • All 1¼ eyepiece adapters are interchangeable with our focuser draw tubes and come with a brass compressing ring.
  • All 1¼ eyepiece adapters have a 48 mm thread machined in the back to accommodate 2 inch filters.
Note: For some applications such as 1¼ inch diagonals the flange will prevent the diagonal from seating flush with the adapter.

Standard Adapter - Back to Eyepiece Adapters List

Generally used on refractor style telescopes, but can be used with Newtonians in certain situations depending on where the focal point resides. Our Standard Adapter can be used where zero length is not a consideration. It uses a thumb screw on the body of the adapter to hold the 1 ¼ eyepieces and the adapter is held in place by the thumb screw/s in the draw tube.

  • All 1¼ eyepiece adapters are interchangeable with our focuser draw tubes and come with a brass compressing ring.
  • All 1¼ eyepiece adapters have a 48 mm thread machined in the back to accommodate 2 inch filters.