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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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CA$42.00 - CA$42.00
CA$42.00
CA$42.00 - CA$42.00
CA$42.00

Dew-Not Heater Strip - 32mm Guide Scope or 1.25" Eyepiece

DN002
Only 3 left!

Fits 1.25" Eyepieces and small finderscopes Total Strip Length: 6.5" (16.5cm) Heater Element Length: 5.5" Power Consumption: 3.1W at 12V DC Curren...

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CA$42.00 - CA$42.00
CA$42.00
CA$42.00 - CA$42.00
CA$42.00
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CA$56.00 - CA$56.00
CA$56.00
CA$56.00 - CA$56.00
CA$56.00

Dew-Not Heater Strip - 4" Scope

DN005

Length: 15.4" (39 cm) Fits: 4" Telescope OTAs and Dew Shields Power: 7.3 Watts at 12V DC Current Draw: 0.61 Amps Connection: 6' Cord with Mol...

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CA$56.00 - CA$56.00
CA$56.00
CA$56.00 - CA$56.00
CA$56.00
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CA$62.00 - CA$62.00
CA$62.00
CA$62.00 - CA$62.00
CA$62.00

Dew-Not Heater Strip - 5" Scope

DN006

Fits: 5" Telescopes Total Strip Length: 16.75" (42.5cm) Heating Element Length: 15.75" Power: 7.9W at 12V DC Current Draw: 0.66A Technology:...

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CA$62.00 - CA$62.00
CA$62.00
CA$62.00 - CA$62.00
CA$62.00
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CA$43.00 - CA$43.00
CA$43.00
CA$43.00 - CA$43.00
CA$43.00

Dew-Not Heater Strip - 50mm Guide Scope or 2" Eyepiece

DN003

8" Active Heating Element Length Designed for 2" Eyepieces and 50mm Guide Scopes 4.2W Power Consumption 0.35A Current Draw at 12V DC 9.0" Total St...

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CA$43.00 - CA$43.00
CA$43.00
CA$43.00 - CA$43.00
CA$43.00
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CA$67.00 - CA$67.00
CA$67.00
CA$67.00 - CA$67.00
CA$67.00

Dew-Not Heater Strip - 6" Scope

DN007

Total Length: 20.5" (52.1cm) Designed for: 6" Telescopes Power Consumption: 9.6 Watts at 12V DC Current Draw: 0.80 Amps Connection: Long Cord with...

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CA$67.00 - CA$67.00
CA$67.00
CA$67.00 - CA$67.00
CA$67.00
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CA$71.00 - CA$71.00
CA$71.00
CA$71.00 - CA$71.00
CA$71.00

Dew-Not Heater Strip - 7" Scope

DN008
Only 4 left!

Heater Element Length: 24" Total Strip Length: 25.0" (63.5cm) Designed For: 7" Telescope OTAs Power Consumption: 11.8 W at 12V DC Connection:...

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CA$71.00 - CA$71.00
CA$71.00
CA$71.00 - CA$71.00
CA$71.00
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CA$77.00 - CA$77.00
CA$77.00
CA$77.00 - CA$77.00
CA$77.00

Dew-Not Heater Strip - 8" Scope

DN009

Fits 8" Schmidt-Cassegrain and similar telescopes 30.0" (76.2cm) strip length with 29" heating element 14 W power consumption at 12V DC Draws 1.18...

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CA$77.00 - CA$77.00
CA$77.00
CA$77.00 - CA$77.00
CA$77.00
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CA$83.00 - CA$83.00
CA$83.00
CA$83.00 - CA$83.00
CA$83.00

Dew-Not Heater Strip - 9" Scope

DN010
Only 5 left!

Fits 9" Schmidt-Cassegrain and other OTAs 33" (83.8cm) Strip Length 32" Active Heater Element Length 15.5W Power Draw at 12V DC Thick-Film Heater ...

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CA$83.00 - CA$83.00
CA$83.00
CA$83.00 - CA$83.00
CA$83.00
CA$95.00 - CA$95.00
CA$95.00
CA$95.00 - CA$95.00
CA$95.00

Dew-Not Heater Strip - Binoviewer

DN017
Only 2 left!

Dual 6.0" heater strips designed for binoviewers 5" active heating element length per strip Operates on 12V DC power Low 5.6 W total power consump...

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CA$95.00 - CA$95.00
CA$95.00
CA$95.00 - CA$95.00
CA$95.00
CA$83.00 - CA$83.00
CA$83.00
CA$83.00 - CA$83.00
CA$83.00

Dew-Not Heater Strip - Hand Controller

DN016
Only 5 left!

Total Strip Length: 4.5" (11.4 cm) Heating Element Length: 3.5" Power Consumption: 2.5W at 12V DC Attachment: Dual Rubber Bands Compatibility: Sta...

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CA$83.00 - CA$83.00
CA$83.00
CA$83.00 - CA$83.00
CA$83.00
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CA$45.00 - CA$45.00
CA$45.00
CA$45.00 - CA$45.00
CA$45.00

Dew-Not Heater Strip - Rigel Quick Fix

DNRQ

Custom-designed to fit the Rigel QuikFinder Prevents dew formation on finder optics Operates on standard 12V DC power 6-foot cable with a universa...

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CA$45.00 - CA$45.00
CA$45.00
CA$45.00 - CA$45.00
CA$45.00
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CA$60.00 - CA$60.00
CA$60.00
CA$60.00 - CA$60.00
CA$60.00

Dew-Not Heater Strip - Telrad Heated Shield

DN018
Only 4 left!

Custom-fit for Telrad finders Efficient 1.44W power consumption Operates on standard 12V DC power Draws only 0.12 A of current Slides on for easy ...

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CA$60.00 - CA$60.00
CA$60.00
CA$60.00 - CA$60.00
CA$60.00
CA$74.00 - CA$74.00
CA$74.00
CA$74.00 - CA$74.00
CA$74.00

Farpoint Desiccant Cap - 1.25"

FAP-FP326
Only 2 left!

Moisture is a menace to fine optics. Alleviate this threat with Farpoint 1.25 Inch Desiccant Cap for closed tube telescopes with 1.25" focusers.Fin...

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CA$74.00 - CA$74.00
CA$74.00
CA$74.00 - CA$74.00
CA$74.00
CA$34.00 - CA$140.00
CA$34.00 - CA$140.00
CA$34.00 - CA$140.00
CA$34.00

Farpoint Flexible Dew Shield - for Celestron & Meade

Options available
4 variants in stock

Farpoint Dew Shield is a virtually indestructible cover. Simply attach the flexible cover to the front of the optical tube to prevent moisture bu...

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CA$34.00 - CA$140.00
CA$34.00 - CA$140.00
CA$34.00 - CA$140.00
CA$34.00
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CA$74.00 - CA$74.00
CA$74.00
CA$74.00 - CA$74.00
CA$74.00

Farpoint Reusable Dry Pack - 4 Pack

FAP-FP331

Farpoint Reusable Dry Pack – 4 Pack is a set of four rechargeable desiccant packs that can be stored in cases to absorb any residual dew from obser...

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CA$74.00 - CA$74.00
CA$74.00
CA$74.00 - CA$74.00
CA$74.00
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Nanuk Reusable Desiccant Container
CA$19.95 - CA$19.95
CA$19.95
CA$19.95 - CA$19.95
CA$19.95

Nanuk Reusable Desiccant Container

NK-30-90016-K

Reusable desiccant canister for long-term moisture control Actively prevents rust, corrosion, mold, and mildew Ideal for protecting optics and ele...

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CA$19.95 - CA$19.95
CA$19.95
CA$19.95 - CA$19.95
CA$19.95
Orion Optics UK AG8 matching Carbon Fibre Dew Shield
CA$560.00 - CA$560.00
CA$560.00
CA$660.00
CA$660.00 - CA$660.00
CA$660.00

Orion Optics UK AG8 matching Carbon Fibre Dew Shield

OOUK-AG8-MATCHING-CARBON-FIBRE-DEW

Carbon fibre construction Slides directly onto the AG8 tube Reduces dew formation and stray light Description Specifications In the Box Warrant...

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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
Orion Optics UK Carbon Dew Heater for 18″ ODK
CA$1,598.00 - CA$1,598.00
CA$1,598.00
CA$1,598.00 - CA$1,598.00
CA$1,598.00

Orion Optics UK Carbon Dew Heater for 18″ ODK

OOUK-TUBE-DEW-HEATER-ODK18TR-CARBON

Custom-designed for 18″ Orion Optics UK ODK Truss telescopes Lightweight and rigid carbon fiber construction Provides uniform heat to prevent dew ...

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CA$1,598.00 - CA$1,598.00
CA$1,598.00
CA$1,598.00 - CA$1,598.00
CA$1,598.00
Orion Optics UK Carbon Dew Heater for 20″ ODK
CA$2,164.00 - CA$2,164.00
CA$2,164.00
CA$2,164.00 - CA$2,164.00
CA$2,164.00

Orion Optics UK Carbon Dew Heater for 20″ ODK

OOUK-TUBE-DEW-HEATER-ODK20TR-CARBON

Custom-fit for Orion Optics UK 20" ODK Telescopes Prevents dew formation on primary mirror and corrector optics Lightweight and rigid carbon fiber...

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CA$2,164.00 - CA$2,164.00
CA$2,164.00
CA$2,164.00 - CA$2,164.00
CA$2,164.00
Orion Optics UK Carbon Dew Heater for 24″ Orion Optics UK Telescopes
CA$3,015.00 - CA$3,015.00
CA$3,015.00
CA$3,015.00 - CA$3,015.00
CA$3,015.00

Orion Optics UK Carbon Dew Heater for 24″ Orion Optics UK Telescopes

OOUK-TUBE-DEW-HEATER-ODK24TR-CARBON

Custom-fit for 24-inch Orion Optics UK ODK telescopes Rigid carbon fibre construction for uniform heat transfer Prevents dew formation on primary ...

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CA$3,015.00 - CA$3,015.00
CA$3,015.00
CA$3,015.00 - CA$3,015.00
CA$3,015.00
Orion Optics UK Carbon Dew Heater for AG10/ODK10
CA$664.00 - CA$664.00
CA$664.00
CA$664.00 - CA$664.00
CA$664.00

Orion Optics UK Carbon Dew Heater for AG10/ODK10

OOUK-TUBE-DEW-HEATER-AG10-ODK10

Custom-designed for Orion Optics UK AG10 & ODK10 telescopes Lightweight and rigid carbon fibre construction Actively prevents dew formation on...

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CA$664.00 - CA$664.00
CA$664.00
CA$664.00 - CA$664.00
CA$664.00
Orion Optics UK Carbon Dew Heater for AG12/ODK12
CA$767.00 - CA$767.00
CA$767.00
CA$767.00 - CA$767.00
CA$767.00

Orion Optics UK Carbon Dew Heater for AG12/ODK12

OOUK-TUBE-DEW-HEATER-AG12-ODK12

Custom-designed for Orion Optics UK AG12 and ODK12 astrographs Lightweight, rigid carbon fibre construction Provides even heat distribution to pre...

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CA$767.00 - CA$767.00
CA$767.00
CA$767.00 - CA$767.00
CA$767.00
Orion Optics UK Carbon Dew Heater for AG14/ODK14
CA$871.00 - CA$871.00
CA$871.00
CA$971.00
CA$971.00 - CA$971.00
CA$971.00

Orion Optics UK Carbon Dew Heater for AG14/ODK14

OOUK-TUBE-DEW-HEATER-AG14-ODK14

Custom-fit for Orion Optics UK AG14 and ODK14 astrographs Rigid carbon fiber construction for durability and efficiency Ensures uniform heat distr...

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CA$871.00 - CA$871.00
CA$871.00
CA$971.00
CA$971.00 - CA$971.00
CA$971.00
Orion Optics UK Carbon Dew Heater for AG16/ODK16
CA$974.00 - CA$974.00
CA$974.00
CA$974.00 - CA$974.00
CA$974.00

Orion Optics UK Carbon Dew Heater for AG16/ODK16

OOUK-TUBE-DEW-HEATER-AG16-ODK16

Custom designed for Orion Optics UK AG16 and ODK16 astrographs Lightweight, rigid carbon fiber construction Provides even, gentle heat to prevent ...

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CA$974.00 - CA$974.00
CA$974.00
CA$974.00 - CA$974.00
CA$974.00

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.