Direct replacement spiders

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Optional Features for Secondary Mounts

Keep your secondary mirror dew-free all night long. Two spider vanes conduct the power to the built-in heater in the mirror holder so there are no wires to thicken the spider vanes. It can be powered by any battery source up to 12 volts DC. The power source can be either a battery wired directly, or any of the commonly available dew controllers on the market (e.g. Kendrick). A red LED power indicator is recessed into the front face to prevent stray light from interfering with imaging.

When operated at full voltage (~12v DC) the heater will clear existing dew in about fifteen minutes. The heater can also be used in a "preventative mode" with as little as 3 volts.

The anti-dew heater is available for 4-vane, 3-vane, and Cassegrain secondary mounts with secondary sizes of 1.83" or larger. Included is a supplemental instruction sheet. This option is not available separately, and must be ordered when you order the spider. For a convenient method of connecting the heated spiders to your power source, see our optional custom interface cables below.


Price (US$)

Anti-dew heater option

add $45.00

For secondary offsets greater than 0.1" (2..5mm), it can be built into the spider by shortening and lengthening opposite vanes. When ordering this option, specify both the offset amount and the orientation.

This option is not available separately, and must be ordered when you order the spider.


Price (US$)

Built-in offset


This kit replaces the standard collimation set screws with finger-adjustable screws. They work for both straight-vane and curved secondary mounts with secondary mirror sizes 1.83" and larger. The thumbscrews feature fully-threaded aluminum shafts, ground tips, and a custom-designed finger knob that doesn't protrude into the light path. Made in the U.S.A.


Price (US$)

Finger adjustable collimation kit for 1.83" to 63.0mm secondary holder sizes. Also fits all Direct Replacement spider kits; #10-24 threading, 3" length


Finger adjustable collimation kit for 2.60" to 90.0mm secondary holder sizes; #10-24 threading, 4" length


Finger adjustable collimation kit for 4.00" and larger heavy-duty secondary holder sizes; 1/4"-20 threading, 5" length


Conveniently connect your Protostar spider with the built-in anti-dew heater to your commercial power source (ZWO, Kendrick, etc). One end has either a RCA or right-angle 5.5mm phono plug. Cut the wire to length for your application and crimp on the included ring lugs. Custom insulating bushings also included. Download the installation instructions for the anti-dew heated spiders to learn more.



Price (US$)

Anti-dew heater hookup wire with right-angle 5.5mm male plug (30-inches length)



Anti-dew heater hookup wire with RCA style male plug (36-inches length)



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