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Lunt Solar 1.25" Rack & Pinion Focuser with 10:1 Fine Focus

Lunt Solar 1.25" Rack & Pinion Focuser with 10:1 Fine Focus

$231.20 USD
$289.00 USD $231.20 USD
Sale Sold out
Shipping calculated at checkout.

Introducing the New 1.25 Rack & Pinion Focuser with 10:1 Fine Focus from Lunt Solar

Pre-order Pricing  -  Ships the last week of April 2026

Precision focusing at high magnifications demands more than standard rack and pinion
mechanisms can deliver. While our standard focuser addresses the fundamental limitations of helical systems, the 10:1 dual-speed variant takes focus control to an entirely new level of refinement.
The integrated 10:1 reduction gearing provides the micro-adjustment capability essential for critical focus applications like solar imaging, planetary observation, and high-power visual work where the difference between good focus and perfect focus determines image quality.

Technical Specifications and Design Analysis

Dual-Speed Mechanism

The focuser incorporates a precision planetary gear reduction system alongside the primary rack and pinion drive. The coarse focus knob provides rapid positioning across the full travel range, while the 10:1 fine focus knob enables micro-adjustments measured in thousandths of an inch.

Key Specifications:

Parameter

Value

Focuser Size

1.25"

Draw Tube Drive

Rack and Pinion

Fine Focus Ratio

10:1 reduction

Draw Tube Travel

0.5"

Coarse Focus Resolution

Standard rack engagement

Fine Focus Resolution

±0.0002" per knob rotation

Rotatable

Yes

Compression Ring

Yes

Positioning Accuracy

±0.001 inches (±0.025mm)

Load Capacity

6-8 pounds (2.7-3.6 kg)

Backlash

<0.0005 inches when properly adjusted

Materials

CNC machined Aluminum and Brass

 

Mechanical Construction

The Lunt Solar 1.25" 10:1 focuser employs CNC-machined aluminum and brass components,
providing optimal thermal expansion characteristics and corrosion resistance for even the most

rigorous astronomical applications. The dual-speed mechanism utilizes hardened steel gearing within the reduction assembly to ensure consistent performance across thousands of focus cycles.

Shipping calculated at checkout. Free shipping on qualifying orders over $200

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Lunt Solar 1.25" Rack & Pinion Focuser with 10:1 Fine Focus
From
$231.20 USD
$289.00 USD $231.20 USD
Sale Sold out

10:1 Fine Focus System

The integrated fine focus mechanism delivers exceptional precision through a carefully
engineered planetary gear reduction:
● 10:1 reduction ratio — One full rotation of the fine focus knob produces 1/10th the draw tube movement of the coarse knob
● Zero-play gear meshing — Precision-ground gears eliminate mechanical slop in the reduction train
● Concentric knob design — Fine and coarse adjustment knobs share a common axis for intuitive operation
● Smooth, continuous adjustment — No detents or click-stops to interrupt fine focusing

This level of control proves essential when working at high magnifications where atmospheric
seeing can vary moment to moment, requiring constant micro-adjustments to maintain optimal
focus.

Experience Precision

Internal Brake System

The integrated brake system addresses gravitational moment loading through a controlled friction mechanism.
● Variable drag control — Adjustable tension accommodates different equipment weights
● Consistent friction characteristics — Maintains position without focus drift
● Positive locking capability — Full lock available for imaging sessions
● Reduced mechanical stress when locked — Distributed load paths protect fine focus
gearing

Experience Precision

Compression Ring Clamping System

The focuser incorporates a brass compression ring system for accessory retention, replacing
conventional set screw mechanisms:

● Uniform clamping force distribution around the full circumference of inserted accessories
● Elimination of point-stress concentrations that can damage precision optical components
● Reduced risk of optical misalignment due to asymmetric clamping forces
● Improved repeatability in accessory positioning

Experience Precision

Why 10:1 Fine Focus Matters

Critical Focus Applications

At magnifications exceeding 150x, the depth of focus narrows dramatically. A standard focuser's minimum adjustment increment may exceed the entire depth of focus zone, making precise focus impossible. The 10:1 reduction transforms coarse movements into micro-adjustments that fall well within even the narrowest critical focus zones.

Practical Impact:

Application Depth of Focus Standard Focuser Min. Adjustment 10:1 Focuser Min. Adjustment
Low-power visual (50x) ~0.020" ~0.005" ✓ ~0.0005" ✓
Medium-power visual (150x) ~0.007" ~0.005" ✓ ~0.0005" ✓
High-power visual (300x) ~0.003" ~0.005" ✗ ~0.0005" ✓
Solar imaging ~0.002" ~0.005" ✗ ~0.0005" ✓

Solar Imaging Excellence

Solar imaging demands the finest focus control available. Prominences, filaments, and surface granulation reveal themselves only when focus is absolutely precise. The 10:1 mechanism allows photographers to "walk" through the focus zone in minute increments, finding the exact point where detail snaps into clarity.

Visual Observation at High Power

When observing fine solar detail visually the spicules along the limb, intricate filament structure, or subtle surface texture the 10:1 fine focus enables real-time adjustment as atmospheric conditions shift. Observers can track optimal focus through seeing variations rather than hunting back and forth across the focus zone.

Performance Comparison: 10:1 vs. Standard Focusers

Precision and Repeatability

Parameter Helical Focuser Standard R&P 10:1 Dual-Speed
Minimum adjustment ~0.010" ~0.005" ~0.0005"
Backlash 0.005-0.015" <0.001" <0.0005"
Focus repeatability Poor Good Excellent
High-mag suitability Poor Adequate Excellent

Operational Advantages

The dual-speed design provides the best of both approaches:

  • Rapid coarse adjustment for initial positioning and equipment changes
  • Ultra-fine adjustment for critical focus optimization
  • Seamless transition between speeds with concentric knob arrangement

No compromise in load capacity or mechanical stability

Uncompromising Craftsmanship

Uncompromising Craftsmanship

Every Lunt telescope is meticulously hand-built and precision-tested in-house to deliver unmatched optical performance. Nothing leaves our hands without meeting exacting standards.

Concierge-Level Support

Concierge-Level Support

From expert bench testing to personalized US-based support, our team ensures a seamless experience.

Professional-Grade Imaging

Professional-Grade Imaging

Unlock the full potential of your observations with premium imaging solutions designed to capture the sun’s finest details.

Trusted by NASA

Trusted by NASA

Chosen for mission-critical observation, our award-winning team partnered with NASA to live-stream the 2024 Solar Eclipse—testament to the precision and reliability of our instruments.

Performance Without Equal

Performance Without Equal

Lunt telescopes are engineered for those who demand the best—offering elite capability, flawless build quality, and enduring value.

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Crafted for discerning observers and professionals, Lunt telescopes deliver world-class optical performance, engineered in the USA with the highest-grade materials and attention to every detail.

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