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Secondary mounts FAQ

How to order secondary mounts


4-vane mounts

3-vane mounts

Curved mounts

ULS Quartz mirrors

Flocked light trap mat'l


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Thin vanes for low diffraction.
Unique simplified collimation procedure.
Optional anti-dew heater available.
Two mirror mounting methods to accommodate any mirror size.
Made from corrosion-proof materials.
Graphite-impregnated flat black finish.
Includes mounting hardware, drill bit, and installation instructions.

Our 3-vane spider design has 1/4 less total diffraction compared to 4-vane models. Bright field objects will appear to have six diffraction spikes spaced at 60° intervals, but the spikes are half as bright compared to a 4-vane spider (see diffraction comparison). The 3-vane mountings feature the same simplified collimation as the 4-vane models, and are available for mirror sizes from 0.75” to 2.60” (minor axis size). Available in metric threaded versions. Made in the U.S.A.

Read how to order secondary mounts...

More detailed information about this product...

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Download the installation instructions for secondary mounts.

See also:
4-vane secondary mounts.

Available Options
An anti-dew heater, built-in offset, and metric threading are optional features you can have built in to your secondary mount. See more details...

Prices include both spider and mirror holder.

The tube ID ranges shown in the table are for pricing purposes only, and the spiders are not adjustable over this wide range. We make your spider to fit your exact tube requirements. When ordering, please provide the actual tube (or cage) inside diameter. We will make your spider slightly smaller to permit proper vane tensioning.

The dimensions in the table are in inches.

Note: Spiders are custom-made for your inside diameter (ID), and are not adjustable over the ranges shown in the table below. When ordering, provide the information described on the ordering information page.

Secondary size

4.50" to 11.50" tube ID

11.51" to 13.50" tube ID

13.51" to 18.00" tube ID


























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