Do I need a dew heater for a Newtonian telescope?

Chris Klein, Amateur Astronomy Advisor

By Chris Klein

Updated:

Do you own a Newtonian telescope? If so, have you ever considered using a dew heater? If not, then you’re missing out!

A dew heater is a perfect addition to your Newtonian telescope. Its primary purpose is to prevent condensation buildup on your mirrors, ensuring greater clarity and detail.

In this article, you get

To explore what a dew heater is and how it works

To learn how temperature and humidity affect performance

To identify if your particular telescope needs one

Tips and suggestions on which type of dew heater best suits your needs

By the end of this article, you’ll have all the information you need to use a dew heater for your Newtonian reflector.

Let’s dive right in.

INTRODUCTION: DO I NEED A DEW HEATER FOR A NEWTONIAN TELESCOPE?

A dew heater may seem like an unnecessary purchase at first, but it can have some hidden benefits.

Warmed optics can provide sharper images and improved contrast, making them worth investing in. Dew heaters can also help significantly reduce the risk of your telescope’s optics becoming wet due to condensation.

When it comes to a Newtonian telescope, one of the most important things is to keep the mirrors dry. Unfortunately, this is usually easier said than done!

Primary mirrors tend to dew up when stored, although they rarely dew up during use. Prolonged exposure to dew will degrade the coatings on your optics over time; this is why investing in a dew heater could be beneficial in some cases.

IDENTIFY IF YOUR NEWTONIAN TELESCOPE NEEDS A DEW HEATER

When the temperatures drop at night, moisture in the air will condense on all cold surfaces, like your mirrors.

To effectively prevent this from happening and keep your optics dry and clear throughout the night sky observations, you’ll need a dew heater solution.

The items required are simple: a dew heater band for each telescope, camera lens or eyepiece you want to keep dry, and a controller with a power source to turn them on.

Other essential factors include portability, noise output levels (if any), heat output levels, and equipment needed for setup.

There are many dew heater models available. It’s important to carefully select the correct type of dew heater for your telescope based on size and individual power needs.

With careful selection combined with a practical application process, your nighttime stargazing sessions will stay dry, giving you crystal-clear views into space!

HOW TO SELECT THE RIGHT TYPE OF DEW HEATER FOR YOUR NEWTONIAN TELESCOPE

For those of us who have Newtonian telescopes, it’s essential to know when you might need a dew heater.

Suppose you observe from an area where dew forms on the outside of your telescope or its components. Having a dew heater can be essential to maintain optimal viewing conditions.

The two main types of dew heaters are stick-on heaters and strap-on heaters.

STICKY DEW HEATERS

Sticky heaters are very easy to use and best for small Newtonian Telescopes with relatively stationary secondary mirrors. A stick-on heater is attached directly to the rear surface of the telescope’s secondary mirror.

It’s essential to check the stability of your telescope before using a sticky heater for Newtonians with removable secondary mirror assemblies.

STRAP-ON DEW HEATERS

Strap-on heaters are adjustable and are best for use on telescopes with rotating or removable secondary mirror assemblies, as they provide more flexibility in placement and installation.

While setting up the strap-on heater is more time-consuming than sticking one on the back of your OTA, it can help protect your hardware if misused.

Now that you’ve learned how to select the correct type of dew heater for your Newtonian telescope, you’ll want to properly install and use it to get the most out of your observations!

Follow the manufacturer’s instructions when setting up and operating your dew heater to guard against damage.

EXPLORE HOW TEMPERATURE AND HUMIDITY AFFECT THE PERFORMANCE OF A TELESCOPE DEW HEATER

Understanding how temperature and humidity affect the performance of a telescope dew heater is essential.

Dew happens when something cools down below a particular “dew point.” The dew point will vary depending on the degree of humidity in the air.

For example, when your telescope’s mirrors become cooler than the ambient temperature, there is likely to be moisture present that could lead to fogging or frosting at any point during your observing session, even as early as 5 minutes in! This is also true if you’re using your Newtonian for terrestrial viewing.

Fortunately, some great products are available, including Dew Heater Controllers, DIY Dew Controllers, and Heater Straps for Telescopes and Eyepieces.

FIND OUT WHAT FEATURES YOU SHOULD LOOK FOR IN A TELESCOPIC DEW HEATER

The size of the dew heater matters when selecting one for your telescope.

All heating elements perform at the same voltage, and choosing an appropriate size allows you to get optimal performance to avoid fogging.

At the same time, if you plan on using multiple heaters at once, consider investing in a controller with numerous channels. Having a multi-channel controller makes things much easier when operating them.

Remember that buying good heaters is better than just using a shield.

TIPS AND STRATEGIES ON MAINTAINING YOUR NEWTONIAN TELESCOPE DEW HEATER

Using a dew heater on your Newtonian telescope can be a great way to prevent dew from forming and negatively affecting your viewing and astrophotography sessions.

But before you can begin to use a dew heater, it is essential to know what dew is and how it affects your telescope.

Dew does not simply “fall” from the sky. It condenses from the surrounding air onto any object colder than the air’s dew point. So, to combat this issue, you need to understand the enemy and take effective countermeasures.

A dew shield typically fits onto the front of your telescope and helps combat receiving too much stray light while keeping its surface temperature above the ambient air temperature.

Due to its physical form factor, you must ensure it fits your particular model properly to fulfill its jobs well.

Using a dew shield not only protects from possible damage caused by condensation, but as a bonus, you might also increase contrast in photos taken with your telescope due to its light baffle feature.

All-in-all, this is one handy accessory every stargazer should consider adding to their arsenal for better viewings in all climates!

SUMMARY

Thank you for reading my article, “Do I need a dew heater for a Newtonian telescope?”

A dew heater can be an invaluable addition if you’re looking for improved optics in your Newtonian telescope. However, each situation is unique and requires careful consideration to select the correct type of dew heater.

Pay attention to the temperature and humidity levels when conducting your observations, research the features that best suit your telescope, and measure twice, install once!

Whether you’re just getting started with astronomy or an experienced astronomer, having the right equipment can make all the difference.

About the Author

Chris Klein, Amateur Astronomy Advisor

Chris Klein is an amateur astronomy advisor, astrophotographer, and entrepreneur. Go here to read his incredible story "From $50,000 in Debt to Award-Winning Photographer Living in Switzerland". If you want to send Chris a quick message, then visit his contact page here.