Optional features for straight-vane secondary mounts
 With the optional built-in anti-dew heater, your secondary mirror will remain dew-free all night long. The spider vanes conduct the electricity, so there are no wires to thicken the spider vanes. A red LED power indicator is recessed into the front face to prevent stray light from interfering with CCD imaging. (Due to our tooling, the LED is omitted on 3-vane mounts ordered with the antidew heater option.)
The anti-dew heater requires a DC power source that you supply (typically a battery). When operated at full voltage (~12 VDC), the heater will clear existing dew in about fifteen minutes. The heater can also be used in a "preventative mode" (i.e., turned on before dew forms) 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 1.52" or larger. The anti-dew heater cannot be retrofitted to existing secondary mounts. Includes supplemental instruction sheet.
(Note: The anti-dew heater is not self-powered, and requires power from an external source that you provide. Read more (110 kB pdf) about how to install and use secondary mounts with the anti-dew heater.)
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Price (US$)
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Anti-dew heater for 1.52", 1.83", and 2.14" secondary mounts
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add $34.00
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Anti-dew heater for 2.60" and 3.10" secondary mounts
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add $38.00
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Anti-dew heater for 3.50" and 4.00" secondary mounts
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add $42.00
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 Large or fast Newtonian telescopes on equatorial or GOTO mountings usually require the secondary mirror to be offset a small distance away from the focuser. If the offset requirement is more than about 1/8” (3 mm), you can have this built into the spider for a cleaner installation. The spider will be custom manufactured with asymmetrical vane lengths.
When ordering this option, provide the offset amount and which orientation you will use (see image to the right). The "split" orientation is most common, and is how we will incorporate the offset unless you specify the "aligned" offset.
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Price (US$)
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Built-in spider offset for any size secondary mount
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add $7.50
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 By selecting this option, the lugs on the spider vanes and the collimation screws will use M5 threads instead of English threads. This option is available only for straight-vane secondary mounts.
Note: There is no extra charge for this option, but the screws that attach the spider to the tube are not included. Use screws with M5-0.8 threads (stainless steel recommended), and choose a length such that at least 3 mm of thread engages the lugs at the tip of the spider vanes.
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Price (US$)
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Metric thread option for spiders (M5-0.8)
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no charge
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