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Closed October 10–12 for Thanksgiving weekend
Closed October 10–12 for Thanksgiving weekend

Dew Prevention and Control

Dew ends more Canadian observing sessions than cloud does. A corrector plate or objective radiating heat to a clear sky drops below the dew point well before the air does, and once condensation forms on a large optic it will not clear on its own. David Astro carries dew prevention and control products in Canada — heater straps, controllers, shields and power distribution — held in stock for fast domestic shipping.

Prevention is straightforward and cheap; recovery is neither. Tell us your telescope aperture and where you observe and we will specify a system that keeps optics clear all night.

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Orion Optics UK Dew Heater for 10" Orion Optics UK Secondary Mirrors
CA$809.00 - CA$809.00
CA$809.00
CA$809.00 - CA$809.00
CA$809.00

Orion Optics UK Dew Heater for 10" Orion Optics UK Secondary Mirrors

OOUK-SECONDARY-DEW-HEATER-AG10-ODK10

Custom-designed for 10" Orion Optics UK AG10 & ODK10 telescopes Prevents dew formation on the secondary mirror Maintains maximum image contras...

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CA$809.00 - CA$809.00
CA$809.00
CA$809.00 - CA$809.00
CA$809.00
Orion Optics UK Dew Heater for 18" Secondary (ODK18Tr)
CA$1,960.00 - CA$1,960.00
CA$1,960.00
CA$1,960.00 - CA$1,960.00
CA$1,960.00

Orion Optics UK Dew Heater for 18" Secondary (ODK18Tr)

OOUK-SECONDARY-DEW-HEATER-ODK18TR-CARBON

Custom-designed for the Orion Optics UK 18" ODK secondary mirror Provides active heating to prevent dew formation Lightweight carbon fibre constru...

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CA$1,960.00 - CA$1,960.00
CA$1,960.00
CA$1,960.00 - CA$1,960.00
CA$1,960.00
Orion Optics UK Dew Heater for Sec. 12″
CA$1,001.00 - CA$1,001.00
CA$1,001.00
CA$1,101.00
CA$1,101.00 - CA$1,101.00
CA$1,101.00

Orion Optics UK Dew Heater for Sec. 12″

OOUK-SECONDARY-DEW-HEATER-AG12-ODK12

Custom-fit for 12" Orion Optics UK telescopes Specifically designed for AG12 and ODK12 models Actively prevents dew formation on the secondary mir...

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CA$1,001.00 - CA$1,001.00
CA$1,001.00
CA$1,101.00
CA$1,101.00 - CA$1,101.00
CA$1,101.00
Orion Optics UK Dew Heater for Sec. 14″
CA$1,193.00 - CA$1,193.00
CA$1,193.00
CA$1,193.00 - CA$1,193.00
CA$1,193.00

Orion Optics UK Dew Heater for Sec. 14″

OOUK-SECONDARY-DEW-HEATER-AG14-ODK14

Custom-designed for 14" Orion Optics UK secondary mirrors Prevents dew formation on the secondary optical surface Ensures maximum image contrast a...

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CA$1,193.00 - CA$1,193.00
CA$1,193.00
CA$1,193.00 - CA$1,193.00
CA$1,193.00
Orion Optics UK Dew Heater for Sec. 16″
CA$1,385.00 - CA$1,385.00
CA$1,385.00
CA$1,385.00 - CA$1,385.00
CA$1,385.00

Orion Optics UK Dew Heater for Sec. 16″

OOUK-SECONDARY-DEW-HEATER-AG16-ODK16

Prevents dew formation on secondary mirrors Custom-designed for 16-inch Orion Optics UK telescopes Essential for all-night imaging and observing s...

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CA$1,385.00 - CA$1,385.00
CA$1,385.00
CA$1,385.00 - CA$1,385.00
CA$1,385.00
Orion Optics UK Dew Heater for Sec. 20″
CA$2,152.00 - CA$2,152.00
CA$2,152.00
CA$2,252.00
CA$2,252.00 - CA$2,252.00
CA$2,252.00

Orion Optics UK Dew Heater for Sec. 20″

OOUK-SECONDARY-DEW-HEATER-ODK20TR-CARBON

Custom-designed for the Orion Optics UK 20-inch ODK secondary mirror Prevents dew formation to maintain maximum image contrast Lightweight carbon ...

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CA$2,152.00 - CA$2,152.00
CA$2,152.00
CA$2,252.00
CA$2,252.00 - CA$2,252.00
CA$2,252.00
Orion Optics UK Dew Heater for Sec. 24″
CA$2,344.00 - CA$2,344.00
CA$2,344.00
CA$2,344.00 - CA$2,344.00
CA$2,344.00

Orion Optics UK Dew Heater for Sec. 24″

OOUK-SECONDARY-DEW-HEATER-ODK24TR-CARBON

Custom-fit for the Orion Optics UK 24" ODK secondary mirror Prevents dew formation to maintain image contrast and brightness Constructed from ligh...

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CA$2,344.00 - CA$2,344.00
CA$2,344.00
CA$2,344.00 - CA$2,344.00
CA$2,344.00
Orion Optics UK OMC-200 Carbon Dew Shield (screw fitting)
CA$560.00 - CA$560.00
CA$560.00
CA$660.00
CA$660.00 - CA$660.00
CA$660.00

Orion Optics UK OMC-200 Carbon Dew Shield (screw fitting)

OOUK-OMC200-CARBON-DEW-SHIELD-SCREW

Designed exclusively for the Orion Optics UK OMC-200 Lightweight, rigid carbon fiber construction Low thermal conductivity minimizes dew formation...

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CA$560.00 - CA$560.00
CA$560.00
CA$660.00
CA$660.00 - CA$660.00
CA$660.00
Sold out
CA$301.00 - CA$301.00
CA$301.00
CA$301.00 - CA$301.00
CA$301.00

Pegasus DewMaster - 5 Channel Digital Dew Heater Controller

PEG-DEWMSTR

DewMaster was made for the visual astronomer. Connect up to five dew heaters and control them individually using PWM duty cycle. Full digital oper...

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CA$301.00 - CA$301.00
CA$301.00
CA$301.00 - CA$301.00
CA$301.00
Sold out
CA$340.00 - CA$340.00
CA$340.00
CA$340.00 - CA$340.00
CA$340.00

Pegasus DewMaster2 - 5 Channel Digital Dew Heater Controller

PEG-DEWMSTR2

Controls five independent dew heater channels Automated dew prevention using included environmental sensor WiFi and USB-C connectivity for remote ...

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CA$340.00 - CA$340.00
CA$340.00
CA$340.00 - CA$340.00
CA$340.00
CA$133.00 - CA$133.00
CA$133.00
CA$133.00 - CA$133.00
CA$133.00

Pegasus DewZap - Dual Channel Dew Heater Controller

PEG-DEWZAP

Dual Channel Control for Two Dew Heaters 5 Amps Per Channel (10 Amps Total) 0-100% Pulse Width Modulation (PWM) Output Accepts 12V-13.8V DC Input ...

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CA$133.00 - CA$133.00
CA$133.00
CA$133.00 - CA$133.00
CA$133.00
CA$35.00 - CA$35.00
CA$35.00
CA$35.00 - CA$35.00
CA$35.00

Pegasus High Accuracy Digital Temperature/Humidity Sensor for DewMaster

PEG-SENS-DEWMSTR

High-accuracy digital temperature sensor High-accuracy digital humidity sensor Provides real-time environmental data Compatible with DewMaster and...

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CA$35.00 - CA$35.00
CA$35.00
CA$35.00 - CA$35.00
CA$35.00
Player One Desiccant Tube for Player One Cooled Cameras
CA$28.00 - CA$28.00
CA$28.00
CA$28.00 - CA$28.00
CA$28.00

Player One Desiccant Tube for Player One Cooled Cameras

POA-Desiccant

Designed for Player One cooled cameras Removes moisture from inside the camera body Prevents condensation on the sensor and optical window Essenti...

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CA$28.00 - CA$28.00
CA$28.00
CA$28.00 - CA$28.00
CA$28.00
CA$83.00 - CA$83.00
CA$83.00
CA$83.00 - CA$83.00
CA$83.00

PrimaLuceLab Dew Heater for 100mm Diameter Telescopes

PLL-PLLFAS100
4 in stock

Fits telescopes with 100mm to 120mm tube diameters Powered by 12V DC via a standard RCA connector Low 500mA power consumption Velcro and elastic s...

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CA$83.00 - CA$83.00
CA$83.00
CA$83.00 - CA$83.00
CA$83.00
CA$91.00 - CA$91.00
CA$91.00
CA$91.00 - CA$91.00
CA$91.00

PrimaLuceLab Dew Heater for 120mm Diameter Telescopes

PLL-PLLFAS120
2 in stock

Designed for 120mm Diameter Telescopes 12V DC Power Input with RCA Connector Velcro and Elastic Band for Secure Fit Integrates with PrimaLuceLab E...

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CA$91.00 - CA$91.00
CA$91.00
CA$91.00 - CA$91.00
CA$91.00
CA$97.00 - CA$97.00
CA$97.00
CA$97.00 - CA$97.00
CA$97.00

PrimaLuceLab Dew Heater for 150mm Diameter Telescopes

PLL-PLLFAS150
2 in stock

Designed for 150mm Diameter Telescopes Fits Optical Tubes from 140mm to 160mm 12V DC Operation with RCA Connector 1000mA Power Consumption Integra...

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CA$97.00 - CA$97.00
CA$97.00
CA$97.00 - CA$97.00
CA$97.00
CA$105.00 - CA$105.00
CA$105.00
CA$105.00 - CA$105.00
CA$105.00

PrimaLuceLab Dew Heater for 180mm Diameter Telescopes

PLL-PLLFAS180
2 in stock

Nominal Telescope Diameter: 180mm Compatible Diameter Range: 160mm - 200mm Power Requirement: 12V DC Power Consumption: 1170mA Connector: RCA D...

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CA$105.00 - CA$105.00
CA$105.00
CA$105.00 - CA$105.00
CA$105.00
CA$125.00 - CA$125.00
CA$125.00
CA$125.00 - CA$125.00
CA$125.00

PrimaLuceLab Dew Heater for 200mm Diameter Telescopes

PLL-PLLFAS200

Fits Telescope Tubes from 180mm to 200mm Diameter Prevents Dew on Corrector Plates and Objective Lenses 12V DC Power with Standard RCA Connector S...

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CA$125.00 - CA$125.00
CA$125.00
CA$125.00 - CA$125.00
CA$125.00
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00

PrimaLuceLab Dew Heater for 250mm Diameter Telescopes

PLL-PLLFAS250

Fits telescopes with 250mm to 300mm tube diameters 12V DC power input via a standard RCA connector Low 630mA power consumption for efficient opera...

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CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00

PrimaLuceLab Dew Heater for 280mm Diameter Telescopes

PLL-PLLFAS280

Fits optical tubes from 280mm to 300mm in diameter Prevents dew formation on primary optics Powered by 12V DC with an RCA connector Low power cons...

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CA$139.00 - CA$139.00
CA$139.00
CA$139.00 - CA$139.00
CA$139.00
CA$153.00 - CA$153.00
CA$153.00
CA$153.00 - CA$153.00
CA$153.00

PrimaLuceLab Dew Heater for 300mm Diameter Telescopes

PLL-PLLFAS300

Fits Telescopes 300mm to 350mm in Diameter Prevents Dew on Refractors and SCTs 12V DC Power Input Standard RCA Connector Velcro Fastener for Secur...

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CA$153.00 - CA$153.00
CA$153.00
CA$153.00 - CA$153.00
CA$153.00
CA$153.00 - CA$153.00
CA$153.00
CA$153.00 - CA$153.00
CA$153.00

PrimaLuceLab Dew Heater for 350mm Diameter Telescopes

PLL-PLLFAS350

Designed for telescopes with 350mm to 360mm tube diameters Prevents dew formation on primary optics Powered by 12V DC via a standard RCA connector...

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CA$153.00 - CA$153.00
CA$153.00
CA$153.00 - CA$153.00
CA$153.00
CA$167.00 - CA$167.00
CA$167.00
CA$167.00 - CA$167.00
CA$167.00

PrimaLuceLab Dew Heater for 450mm Diameter Telescopes

PLL-PLLFAS450

Designed for telescopes with approximately 450mm tube diameters Actively warms optics to prevent dew formation Flexible design with elastic and Ve...

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CA$167.00 - CA$167.00
CA$167.00
CA$167.00 - CA$167.00
CA$167.00
CA$69.00 - CA$69.00
CA$69.00
CA$69.00 - CA$69.00
CA$69.00

PrimaLuceLab Dew Heater for 50mm Diameter Telescopes

PLL-PLLFAS50
7 in stock

Designed for 50mm Diameter Optics Fits Optical Tubes from 40mm to 60mm Low Power Draw at 330mA 12V DC Power with RCA Connector Integrates with Pri...

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CA$69.00 - CA$69.00
CA$69.00
CA$69.00 - CA$69.00
CA$69.00

How Dew Forms and How to Stop It

An optic pointed at a clear sky radiates heat into space and cools below ambient air temperature. When it falls below the dew point, water condenses on it. The fix is to hold the glass a few degrees above ambient, not to heat it aggressively.

  • Heater straps: Resistive bands sized to specific apertures, wrapped near the objective or corrector to keep the glass just above dew point.
  • Dew controllers: Pulse-width controllers that regulate power rather than running heaters continuously, which saves battery and avoids introducing tube currents.
  • Dew shields: Extend the tube beyond the objective, reducing the sky area the optic radiates to. Passive, free to run, and often enough on their own for refractors.
  • Heated eyepiece and finder bands: Small straps for eyepieces, finders and guide scopes, which dew up as readily as the main optic and are often forgotten.
  • Power distribution: Dew heaters draw significant current, and a distribution box sized for the total load prevents voltage sag affecting the mount.
  • Desiccants: Control moisture inside stored equipment, where slow condensation cycling causes long-term damage.

Why Choose David Astro for Dew Control

We observe through Canadian humidity and Canadian cold, which are different problems requiring different amounts of power.

  • Power budgeted for the whole night: We total heater draw against your supply capacity, because a battery that runs the mount for eight hours may run mount plus heaters for three.
  • Sized to aperture: Strap length and wattage are matched to your specific optic. An undersized strap runs at full power and still loses; an oversized one wastes battery and can induce tube currents.
  • Controller recommended, not optional: Running heaters unregulated wastes power and can degrade seeing through the tube. We recommend a controller with any heater purchase.
  • Authorized dealer: Genuine products with manufacturer warranty, in Canadian stock.
  • Ships from Canada: No duties or brokerage fees on Canadian orders.

Dew Control in Canada — Frequently Asked Questions

Is a dew shield enough on its own?
Often for refractors, which have a recessed objective and can use a long shield. Schmidt-Cassegrains, with the corrector at the front, almost always need a heater as well.
How much power do dew heaters draw?
Enough to matter — a large strap can draw several amps at full output. A controller typically cuts average consumption substantially by pulsing rather than running continuously.
Can I use a hair dryer to clear dew?
It works but is a poor solution. Rapid heating creates tube currents that ruin seeing for a long time afterwards, and the dew returns within minutes. Prevention with a low-power heater is far better.
Do I need dew control in winter?
Yes, and frost is the winter version of the same problem. It forms by the same radiative cooling mechanism and is harder to remove without damaging coatings, so prevention matters more, not less.

Losing nights to dew?

Tell us your aperture and power setup and we will specify heaters, a controller and a shield. In Canadian stock, shipped worldwide.