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Focusers and Accessories

Focus is the difference between a sharp image and a nearly sharp one, and holding it across a Canadian night — where temperatures can drop fifteen degrees between dusk and dawn — is a mechanical problem, not a patience problem. David Astro carries focusers and focuser accessories in Canada, from Crayford and rack-and-pinion drawtubes to motor kits, rotators, compression rings and adapter flanges, in Canadian stock.

We fit focusers to telescopes routinely, including retrofits that require a specific flange or drawtube adapter. If you are replacing a stock focuser or adding motorization, tell us the telescope and we will confirm the fit.

Filters

SVBONY Full Metal Finder Scope Dovetail Mounting Set for Telescopes
$12.99 - $12.99
$12.99
$12.99 - $12.99
$12.99

SVBONY Full Metal Finder Scope Dovetail Base and Mounting Plate Set

SV-F9176A

Full Metal Construction for Zero Flexure 42mm Wide Universal Mounting Base Fits Celestron, Orion, Sky-Watcher, and Vixen Telescopes Ideal for Addi...

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$12.99 - $12.99
$12.99
$12.99 - $12.99
$12.99
SVBONY SA406 Eyepiece Adapter for SA401 Spotting Scope to SV230/SV245
$14.05 - $14.05
$14.05
$14.05 - $14.05
$14.05

SVBONY SA406 Eyepiece Adapter for SA401 Spotting Scope to SV230/SV245 - 1.25"

SV-W9170A

Connects SA401 Scope to 1.25" Eyepieces Optimized for SV230 & SV245 Zoom Eyepieces Durable All-Metal Construction Ensures Correct Focus is Mai...

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$14.05 - $14.05
$14.05
$14.05 - $14.05
$14.05
SVBONY SV157 1.25-inch Extension Tube (56mm / 70mm)
$11.19 - $11.19
$11.19
$11.19 - $11.19
$11.19

SVBONY SV157 56mm Extension Tube - 1.25"

SV-W9118A

Adds a fixed 56mm or 70mm of back focus Standard 1.25-inch barrel diameter CNC-machined aluminum for rigidity Matte black interior prevents intern...

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$11.19 - $11.19
$11.19
$11.19 - $11.19
$11.19
SVBONY SV157 1.25-inch Extension Tube
$11.99 - $11.99
$11.99
$11.99 - $11.99
$11.99

SVBONY SV157 70mm Extension Tube - 1.25"

SV-W9118B

Adds Critical Focuser Out-Travel Standard 1.25-inch Barrel Diameter Improves Focus for Astrophotography Cameras CNC-Machined Aluminum Construction...

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$11.99 - $11.99
$11.99
$11.99 - $11.99
$11.99
SVBONY SV158 75mm Extension Tube 2 inch
$13.59 - $13.59
$13.59
$13.59 - $13.59
$13.59

SVBONY SV158 75mm Extension Tube - 2"

SV-W9119A

2-Inch Barrel Diameter CNC-Machined Aluminum Alloy Black Anodized Finish Adds Back Focus for Imaging Description FAQ Specifications In the Box ...

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$13.59 - $13.59
$13.59
$13.59 - $13.59
$13.59
SVBONY SV158 75mm Extension Tube 2 inch
$15.19 - $15.19
$15.19
$15.19 - $15.19
$15.19

SVBONY SV158 90mm Extension Tube - 2"

SV-W9119B

Adds Critical Spacing to 2-inch Focusers Solves Focuser Travel Limitations CNC-Machined Aluminum Alloy Construction Standard 2-inch Barrel Diamete...

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$15.19 - $15.19
$15.19
$15.19 - $15.19
$15.19
SVBONY SV161 1.25-inch Double Helical Micro Focuser
$28.91 - $28.91
$28.91
$28.91 - $28.91
$28.91

SVBONY SV161 Double Helical Micro Focuser - 1.25"

SV-F9173B

Precise 0.05mm adjustment accuracy for fine focusing 10mm of draw tube travel Non-rotating mechanism keeps camera orientation fixed Standard M42x0...

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$28.91 - $28.91
$28.91
$28.91 - $28.91
$28.91
SVBONY SV179 Red Dot Finder Scope with Dovetail Base for Telescope
$13.67 - $13.67
$13.67
$13.67 - $13.67
$13.67

SVBONY SV179 Red Dot Finder Scope with Dovetail Base

SV-W9139B
5 in stock

Intuitive Red Dot Reticle Adjustable Brightness for Day/Night Use Wide, Unmagnified Field of View Standard Dovetail Mounting Base Durable and Ligh...

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$13.67 - $13.67
$13.67
$13.67 - $13.67
$13.67
SVBONY SV179 Red Dot Finder Scope with Universal Two-Hole Fixing Base
$15.19 - $15.19
$15.19
$15.19 - $15.19
$15.19

SVBONY SV179 Red Dot Finder Scope with Two-Hole Fixing Base

SV-W9139A

Intuitive Red Dot Targeting System Adjustable Brightness for Day and Night Use Wide Field of View for Easy Object Location Universal Two-Hole Fixi...

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$15.19 - $15.19
$15.19
$15.19 - $15.19
$15.19
SVBONY SV181 Rack and Pinion Newtonian Reflector Focuser - 1.25"
SVBONY SV181 Rack and Pinion Newtonian Reflector Focuser - 1.25"
$30.99 - $30.99
$30.99
$30.99 - $30.99
$30.99

SVBONY SV181 Rack and Pinion Newtonian Reflector Focuser - 1.25"

SV-W9140A
1 in stock

65mm Focuser Travel 105mm Focuser Tube Length Accepts 1.25'' Eyepieces Fits 114mm-150mm Newtonian Reflectors Durable All-Metal Rack & Pinion D...

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$30.99 - $30.99
$30.99
$30.99 - $30.99
$30.99
SVBONY SV182 6x30 Right-Angle Correct-Image Finder Scope with Bracket
SVBONY SV182 6x30 Right-Angle Correct-Image Finder Scope with Bracket
$32.38 - $32.38
$32.38
$32.38 - $32.38
$32.38

SVBONY SV182 6x30 Right-Angle Correct-Image Finder Scope with Bracket

SV-W9141D
2 in stock

6x Magnification 30mm Aperture 7.5° Field of View 90° Right-Angle, Correct-Image View Fully Multi-Coated (FMC) Optics Description FAQ Specifica...

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$32.38 - $32.38
$32.38
$32.38 - $32.38
$32.38
SVBONY SV182 6x30 Straight Correct-Image Finder Scope with Bracket
SVBONY SV182 6x30 Straight Correct-Image Finder Scope with Bracket
$43.00 - $43.00
$43.00
$43.00 - $43.00
$43.00

SVBONY SV182 6x30 Straight Correct-Image Finder Scope with Bracket

SV-W9141B

6x magnification with a 30mm objective lens Wide 7.5° true field of view for easy object locating Correct-image orientation matches naked-eye view...

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$43.00 - $43.00
$43.00
$43.00 - $43.00
$43.00
SVBONY SV208 8x50 Correct-Image Illuminated Finder Scope
$73.59 - $73.59
$73.59
$73.59 - $73.59
$73.59

SVBONY SV208 8x50 Correct-Image Illuminated Finder Scope

SV-W9160A
1 in stock

50mm Aperture 8x Magnification 7.3° Field of View Correct-Image Orientation Illuminated Crosshair Reticle Description FAQ Specifications In the...

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$73.59 - $73.59
$73.59
$73.59 - $73.59
$73.59
SVBONY SV224 Universal Dovetail Base for Finder Scope Telescope Mount
$10.07 - $10.07
$10.07
$10.07 - $10.07
$10.07

SVBONY SV224 4.2mm Universal Dovetail Base for Finder Scopes

SV-W2370A
2 in stock

Universal dovetail base for finder scopes and other aiming devices Features 4.2mm universal dovetail slots for wide compatibility Equipped with tw...

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$10.07 - $10.07
$10.07
$10.07 - $10.07
$10.07
$9.14 - $9.14
$9.14
$9.14 - $9.14
$9.14

SVBony SV224 Universal Finder Base

SV-W2370B

$9.14 - $9.14
$9.14
$9.14 - $9.14
$9.14
Svbony 1.25" Telescope Eyepiece Adapter Coaxial Lock PETF Inner Ring
$15.99 - $15.99
$15.99
$15.99 - $15.99
$15.99

SVBONY Telescope Eyepiece Adapter with Coaxial Lock and PTFE Inner Ring - 1.25"

SV-F9164A

Adapts M42 threaded accessories to 1.25" focusers and holders Coaxial locking mechanism ensures a self-centering, secure grip PETF inner ring prev...

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$15.99 - $15.99
$15.99
$15.99 - $15.99
$15.99
SVBONY 1.25" Telescope Focuser Adapter M42x0.75 for Reflector
$14.39 - $14.39
$14.39
$14.39 - $14.39
$14.39

SVBONY Telescope Focuser Adapter M42x0.75 for Reflectors - 1.25"

SV-F9163A

Adapts M42x0.75 male threads to accept 1.25" eyepieces and accessories Provides 37mm to 47mm of adjustable focus distance Three locking thumbscrew...

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$14.39 - $14.39
$14.39
$14.39 - $14.39
$14.39
Tele Vue Extension Tube - 2" 2
Tele Vue Extension Tube - 2" 1
$78.00 - $78.00
$78.00
$78.00 - $78.00
$78.00

Tele Vue 2" Extension Tube - 2" Length

TV-X2C-0008

Extension Length: 2 inches (50.8mm) Barrel Diameter: 2 inches Locking Mechanism: Brass clamp ring with single thumbscrew Safety Feature: Undercut ...

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$78.00 - $78.00
$78.00
$78.00 - $78.00
$78.00
Tele Vue Extension Tube - 3.5" 2
Tele Vue Extension Tube - 3.5" 1
$78.00 - $78.00
$78.00
$78.00 - $78.00
$78.00

Tele Vue 2" Extension Tube - 3.5" Length

TV-X3C-0009

Extension Length: 3.5" (89mm) Telescope Connection: 2" Barrel Accessory Connection: 2" Barrel Material: Anodized Aluminum Internal Finish: Matte B...

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$78.00 - $78.00
$78.00
$78.00 - $78.00
$78.00
Tele Vue Eyepiece Barrel Extension - 2" 1
$39.00 - $39.00
$39.00
$39.00 - $39.00
$39.00

Tele Vue 2" Eyepiece Barrel Extension - 1.2" Length

TV-EBX-2120

Adds 1.2" (30.5mm) of Extension For 2" Focusers and Accessories Non-Marring Brass Clamp Ring Dual Thumbscrews for Secure Lock Accepts Standard 2" ...

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$39.00 - $39.00
$39.00
$39.00 - $39.00
$39.00
Tele Vue 2.4" Adapter for 2" Accessories 2
Tele Vue 2.4" Adapter for 2" Accessories 1
$79.00 - $79.00
$79.00
$79.00 - $79.00
$79.00

Tele Vue 2.4" Adapter for 2" Accessories

TV-A2A-1107

Connection Side 1: 2.4" Female Thread for Tele Vue NPis Focusers Connection Side 2: 2" Accessory Barrel with Brass Clamp Ring Material: Anodized A...

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$79.00 - $79.00
$79.00
$79.00 - $79.00
$79.00
Tele Vue Accessory X-Y Mount 1
$130.00 - $130.00
$130.00
$130.00 - $130.00
$130.00

Tele Vue Accessory X-Y Mount

TV-AAM-0001

Independent X-Y Axis Adjustment Universal Mounting Block (MBC-1001) Included Accepts Tele Vue Starbeam, Sol-Searcher, and Piggy-Cam Mounts to Tele...

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$130.00 - $130.00
$130.00
$130.00 - $130.00
$130.00
Tele Vue Block Adptr X-Y Mount 1
$25.00 - $25.00
$25.00
$25.00 - $25.00
$25.00

Tele Vue Block Adptr X-Y Mount

TV-MBC-1001

Function: Adapts Tele Vue X-Y Mount to Ring Mounts Compatibility: Tele Vue AAM-0001, Tele Vue Ring Mounts Material: Black Anodized Aluminum Mounti...

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$25.00 - $25.00
$25.00
$25.00 - $25.00
$25.00
Tele Vue Dovetail for QRB-1002 1
$34.00 - $34.00
$34.00
$34.00 - $34.00
$34.00

Tele Vue Dovetail for QRB-1002

TV-QRD-1006
1 in stock

Accessory Mounting Plate Vixen-Style Dovetail Profile Designed for Tele Vue QRB-1002 Quick Release Bracket Attaches to Telescope Optical Tube or R...

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$34.00 - $34.00
$34.00
$34.00 - $34.00
$34.00

Focuser Mechanics and What Matters Under Load

A focuser has to hold a camera train weighing several kilograms perfectly square to the optical axis while moving in increments of a few microns. Two things determine whether it does: the drive mechanism and the load rating.

  • Crayford focusers: A friction roller on a flat surface, giving smooth, backlash-free travel. Excellent for visual and light imaging loads; can slip under heavy trains, particularly when pointed near zenith.
  • Rack-and-pinion focusers: Toothed engagement that will not slip regardless of load, which is why most heavy imaging trains use them. Modern designs have effectively eliminated the old backlash complaints.
  • Motorized and electronic focusers: Stepper-driven focus with position repeatability, enabling autofocus routines and temperature compensation across a session.
  • Rotators: Precise framing and camera angle control without breaking the imaging train, and essential for optimizing off-axis guide star placement.
  • Compression rings: Replace a single set screw that tilts and marks your barrel with even radial clamping — a small part with a visible effect on star shapes.
  • Adapters and flanges: Telescope-specific mounting plates that let a third-party focuser replace a stock one.

Why Choose David Astro for Focusers and Accessories

Focuser upgrades are one of the most cost-effective improvements in astrophotography, and one of the easiest to order incorrectly.

  • Retrofit fit checks: We identify the adapter flange your specific telescope needs, and confirm that the new focuser's travel and profile will still let you reach focus.
  • Load rating advice: We weigh your intended imaging train against the focuser's rated capacity, including the tilt load that shows up when the tube is near zenith.
  • Authorized dealer: Genuine parts with full manufacturer warranty, serviced in Canada.
  • Canadian stock: In-stock focusers and accessories ship domestically without duties or brokerage charges.
  • In-house repair: We service focuser mechanics and electronics directly, which matters for a component with moving parts that see heavy use.

Focusers in Canada — Frequently Asked Questions

Crayford or rack-and-pinion for imaging?
Rack-and-pinion, once your imaging train exceeds roughly 2 kg. A Crayford's friction drive can slip under load at steep angles, and the slip is often mistaken for focus drift.
Will a motorized focuser fit my existing focuser?
Often yes, through a telescope-specific bracket that couples to the fine-focus shaft. Tell us the focuser model and we will confirm whether a bracket exists or a full replacement is needed.
How much does focus shift with temperature?
Enough to matter. A metal tube contracts measurably over a 15 degree drop, and at fast focal ratios the critical focus zone is only tens of microns. Temperature-compensated autofocus solves it.
Do you carry focusers for older telescopes?
We carry a wide range of adapter flanges covering many discontinued tubes. Send us the make and drawtube diameter and we will check.

Upgrading your focuser?

Tell us your telescope and imaging train weight and we will specify the right focuser and flange. Canadian stock, expert fitting advice.