New GS Series Guide Scopes

PAPO Apochromatic Optical Design
True Star-Color Reproduction

The GS Series guide scopes employ a proprietary 1-inch flat-field PAPO triplet with an ED low-dispersion element. Chromatic aberration, astigmatism, and field curvature are effectively corrected for crisp, pinpoint star images. One scope covers guiding, visual observing, and entry-level deep-sky imaging.

GS-150 GS-200 GS-250 GS-300 GS-350

High-Transmission Coatings + Anti-Reflection Threads
Boost Guiding Sensitivity

Every optical surface receives broadband multi-layer AR coatings to minimize reflections and maximize throughput. Precision-machined anti-reflection threads inside the OTA further suppress stray light for higher contrast images.

CNC Precision Machining
Fine Matte Finish

The tube, rings, and dovetail are CNC-machined from aluminum alloy for an ideal balance of low weight and rigidity. Anodized surfaces resist wear and corrosion in the field, while the refined matte texture delivers a comfortable, non-slip grip.

Modular Design
Highly Expandable

A dedicated matte-black M48 extension tube forms the core of the OTA. Mix and match modules to suit your required back focus—covering visual observing, guiding, and imaging without compromise.

GS-250 Guide Scope + GPM Guide Camera

GS-350 Guide Scope + Diagonal + Eyepiece

GS-350 Guide Scope + Filter Drawer (+ optional EAF) + Deep-Sky Camera

*GS-250 may not reach focus with a diagonal due to limited back focus.

Dual Focuser Configurations
Match Your Workflow

• Rackless focuser (AC version): paired with the FSB-125C rackless focuser. Precision bearing guidance and a classic Crayford mechanism deliver silky-smooth motion with stable collimation—perfect for lightweight manual focusing scenarios.

  

• Rack-and-pinion focuser (AR version): paired with the FSB-125R gear focuser. Bearing-guided gear drive increases load capacity and precision, and it supports ToupTek AAF or third-party motor focusers for automated focusing.

  

Broad Compatibility | Flexible Configurations
Seamless Integration Across Systems

GS Series guide scopes are ready for a wide range of accessories. High-transmission coatings and fully baffled interiors preserve contrast, whether you attach cameras, focusers, or diagonals.

• 1) Supports high-quality imaging with 1-inch and smaller guide or planetary cameras.

  

• 2) Focuser drawtube offers a 1.25-inch inner diameter with an external M42×0.75 thread—connect cooled cameras (optimized for a 1-inch image circle) or add motor focusers such as the ToupTek AAF or IFR focus stations.

  *We recommend pairing with sensor formats up to 1 inch.
  

• 3) Use third-party bayonet-to-M42 adapters to attach mirrorless or DSLR cameras. Adjust the extension tubes to match the flange distance—APS-C sensors are recommended to minimize vignetting.

  

• 4) Modular M48 extension tubes let you swap to shorter tubes when pairing with eyepieces or diagonals.

  

• 5) Tube rings include multiple M5 threaded holes on the top and sides to mount additional accessories.

  

• 6) The dovetail base provides multiple M6 threaded holes plus a 3/8-16 port for quick attachment to tripods or equatorial mounts.

  

All-New Upgrades

Compared with the previous FS series, the new GS family delivers comprehensive improvements from optics to overall performance.

Dimensions

GS-150 GS-200 GS-250 GS-300 GS-350

GS-150AC Dimension Drawing

GS-150AR Dimension Drawing

What's in the Box

The GS series delivers end-to-end upgrades compared with the FS predecessors—from optics and mechanics to usability.

• Guide Scope Packaging Box
• GS-150AC/AR,
  GS-200AC/AR,
  GS-250AC/AR,
  GS-300AC/AR,
  GS-350AC/AR
  Guide Scope
  (with tube rings / dovetail & focuser)
• Guide Scope Dust Cap