For many astronomy enthusiasts, a guide scope often plays a supporting role in the entire astrophotography system. However, ToupTek Astro GS Series Guide Scopes break this mold: it not only provide precise guiding for deep-sky photography but also transform into a high-quality telephoto lens for daytime use. It can even serve directly as a portable APO-level telescope for visual observation of the night sky and distant landscapes, seamlessly transitioning from capturing everyday scenery and dynamic scenes to deep-sky and planetary imaging.
Guide Scope and Planetary or Guide Camera
The GS guide scope is usually used with a planetary or a guide camera up to 1-inch sensors for precise guiding. This is the common use of a guide scope in astrophotography.
Guide Scope and Digital Camera
For daily photography, we can connect the GS Series Guide Scope to various models of mirrorless or DSLR cameras using a universal third-party M42 adapter. If necessary, remove part of the guide scope's extension tube based on the flange distance to meet the required optical path. We recommend pairing it with an APS-C format camera to effectively reduce vignetting at the image edges and achieve frames with a full field of view.
Here are some sample images:
Guide Scope and Deep-sky Camera
The GS Series Guide Scopes feature an M42x0.75 threaded interface at the rear, allowing direct connection to mainstream deep-sky cameras for photography. With a 1-inch sweet spot, it is recommended to pair them with 1-inch or smaller format cameras. Automatic focusing can be achieved when used with ToupTek Astro AAF or the iOptron IFR Auto-Focusing Station.
GS-350 paired with ATR585C, Credit: Wu Yan De She Ying Shi
Here are some sample images taken with deep-sky cameras and GS guide scopes:
GS-150+ATR585C, 600s single exposure, shot during a full moon under Bortle 8 skies.
The image above shows the full APS-C (Half-Frame) coverage of the ATR2600C camera. It marks the image circle coverage areas for three common sensors: IMX533, IMX585, and IMX662, corresponding to their respective fields of view for deep-sky imaging and guide scopes.
Guide Scope and Planetary Camera for Solar and Lunar Imaging
Guide Scope and Eyepiece/Diagonal
With simple modular reconfiguration, the GS Series Guide Scopes easily transform into high-quality portable telescopes. By removing the original short tube from the end of the GS-350 and replacing it with a universal M48 extension tube, you can attach an eyepiece or diagonal. Whether it's the night sky or daytime scenery, everything comes clearly into view.
Specifications of the GS series Guide Scope
The GS series guide scopes have 5 different focal lengths. The AC version comes with a Crayford-style focuser, which provides smooth manual focus and is ideal for light-load astrophotography. The AR version comes with a rack and pinion focuser, which provides high-precision focusing with gear and rack drive. AR version is also compatible with ToupTek Astro AAF, and it supports heavier loads and automated operations.
| Models | Focal Length | Aperture | Focal Ratio |
| GS-150AC/AR | 150mm | 30mm | f/5 |
| GS-200AC/AR | 200mm | 40mm | f/5 |
| GS-250AC/AR | 250mm | 50mm | f/5 |
| GS-300AC/AR | 300mm | 50mm | f/6 |
| GS-350AC/AR | 350mm | 58mm | f/6 |
Spot Diagrams of GS Guide Scopes
The GS series guide scopes feature an optical design of 3-element PAPO (planar apochromatic with integrated field flattener) and a proprietary 1-inch corrected image circle. An ED glass is incorporated to correct chromatic aberration, astigmatism and field curvature effectively. This optical design delivers high resolution and crisp, pinpoint star images. The outstanding optical performance makes the GS series guide scopes equally suitable for guiding, visual observing and entry-level astrophotography.
