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Secondary mounts FAQ

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Direct replacement spiders

4-vane Newtonian spiders

3-vane Newtonian spiders

Curved secondary mounts

Cassegrain secondary mounts

Flocked Light Trap Mat'l

Hi-tack flocked light trap

FlockBoard flocked light trap


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Protostar direct-replacement spiders are made to fit commercial Newtonian telescopes made by Guan Sheng Optics (GSO, Taiwan), Synta (China), and Jinghua Optical Corporation (JOC, China), and these scopes are branded under many names. Our spiders cure common collimation frustrations encountered with the factory spider. Installation takes only minutes since our spider fits into the existing tube holes. It is not necessary to supply your telescope's dimensions when ordering direct-replacement spiders.

Design features

The design is the same as our custom-sized spiders with carbon composite body parts and steel vanes. The holder uses a slip-on shroud to retain the mirror which also covers the edge of the secondary (a significant source of scattered light). A heated version is available for late-night observers and astrophotographers who might encounter dew.

Protostar secondary mounts rarely need collimation tweaking in the field. The clutch disk keeps tip-tilt and rotational adjustments independent and prevents the collimation screws from digging into the back of the holder. After collimation, there is no final lock-down required that usually throws the collimation off again. Made in the USA.

Other useful information

Read how Protostar spiders work.

Download the installation and use instructions.

Choose your telescope's brand


If you don't see your brand or model please contact us. Due to the similarity between brands, we can frequently still provide a spider.

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Protostar P.O. Box 368 New Albany, Ohio 43054 U.S.A. 614-375-3146
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