DIY Solar Filter Telescope: 5-Step Easy Guide

Chris Klein, Amateur Astronomy Advisor

By Chris Klein


Are you an avid telescope user who wants to protect your eyes from the sun’s harmful rays? Then, a DIY solar filter telescope is a great way to view the sun. A DIY solar finder is a specially designed cap that can be fitted to your small telescope, cutting out ultraviolet light and infrared radiation from the sun.

In this article, you get

A brief explanation of how solar filters work and whether they’re worth it

How to make your DIY solar film

How to test your solar filter

An overview on what you can expect to see with your DIY solar filter

By the end of this article, you’ll be able to make your solar filter for your telescope, know how to test and use it safely, and much more!

Let’s dive right in.


Partial Solar Eclipse photo credit Mararie Flickr
Partial Solar Eclipse photo credit Mararie, Flickr

A solar filter DIY is a special homemade solar filter for your telescope that blocks the visible light from the sun. It helps prevent your eyes or digital camera’s sensor from getting burnt by the sun’s light. In addition, it also gives the sun a whiter hue, which is helpful during totality.

Read my article Can you look at a solar eclipse without sunglasses?

A sun filter comes in a variety of forms. For example, you can use cardboard rings or a triangular shipping tube to make your UV filter. These are both easy to make, but if you want more professional results, you can build a DIY solar viewer.

Once you have built your solar viewer, you’ll need to secure it. For instance, you can use rubber bands to hold it together. The rubber bands will help protect your filter assembly and give you a better grip.

Alternatively, you can make a long box and duct tape the ends of two shorter tubes together. You can also use double-sided sticky tape to stick to the telescope tube and ensure a tight fit.

Nevertheless, you’ll need to ensure the box is long enough to get a decent picture of the sun. You can estimate the length by multiplying 0.01 by the inner diameter of the box. For example, a six-foot box you can pick up at Home Depot will produce a solar image of about 0.72 inches.

Are You New To The World Of Telescopes?

If you’re new the world of telescopes, read my articles Why is my telescope upside down?How to Tell if Telescope Needs Collimation, and How to Clean Telescope Mirror: 11-Step Guide.


Yes, it is. In fact, for people who want to take photographs or videos of the sun using a telescope, it is essential to use the proper solar film. The solar window film is rugged polyester, which helps guard against ultraviolet light, glare, and heat.

Read my article Can I take a photo of a solar eclipse?

Solar observing uses several films, producing a bluish or orange image of the solar surface. They are slightly blurry, but they are better than no solar filter. They could be better for visual use with an eyepiece, though.


Silver/Gold Baader AstroSolar Film is perfect for identifying large sunspots through the optical tube. It is a very energy-balanced solar filter sheet for telescopes and does not transmit excess infrared radiation. As a result, Baader Film provides a sharp solar image without compromising the optical quality of the picture.

Due to the double-side metallization process developed for AstroSolar Silver/Gold Film, it stays safe, even when the front of the viewer endures a scratch or moderate abuse.

Additionally, Baader Planetarium offers AstroSolar safety film. This solar film:

  • Produces a clear image while minimizing the effects of atmospheric turbulence
  • Is a non-mechanical, streak-free foil used for telescopes and cameras with no lens
  • Has similar reflective properties to astronomical mirrors

Likewise, Baader Neutral Density (ND) 5.0 Solar Safety Films are excellent glass filters for observing the sun. This is durable, doesn’t alter the telescope’s focus, and works on virtually every lens design. It also doesn’t induce a false color while providing similar protection to the number 14 welder’s glass.


When making a DIY solar film telescope, it is essential to protect your vision. It would be best if you never looked directly at the sun with your telescope; using a filter will help keep your eyes from being damaged.


The first step is to measure your telescope. The measurement will help you to determine the size of the piece of solar film you need.


You will need a square about two inches wider than the front end of your telescope. Make the hole using a razor blade or sharp scissors. Next, you should cut out a circle on your square.


You should then be able to slide the square onto the end of the telescope. It would help if you also cut out a circle on the opposite side of the square. The cutout will help you to protect the center of the square.


Once the cutout is in place, you should tape the solar film onto a piece of tissue. The tape will prevent the film from slipping. You can also use a piece of double-sided tape in overlapping strips.


If you want to add an extra level of security, you can also purchase a wide flat rubber band. The rubber band will provide additional grip for pulling the solar film in and out.


If you’re planning to make your solar filter, it’s a good idea to test it to ensure you’re using a good filter. Otherwise, you’ll damage your equipment and possibly even your eyes.

Before you start, you should gather a variety of materials. The most common material used is thin metal-coated polyester.

However, you should first consider aluminized polyester. These are made specifically for viewing the sun’s visible surface. They offer aluminized material for sound radiation transmission and a coating that prevents the light from damaging the lens.

Once you have your materials, you can begin to create the filter. The first step is to make a cardboard sleeve. It should be long enough to cover your telescope lens’s outer diameter.

Next, you’ll need to test the film. Again, intense artificial light can help you detect pinholes or bright spots. If you notice any of these issues, you should discard the film.

You can use a digital CCD camera if you do not have a light source. The results should look similar to the images you’d get from eclipse glasses.


If you’re looking to start solar observing, it’s essential to know what to expect from a homemade solar filter.

These can be an excellent way to observe the sun, but they are also dangerous if not used properly. For example, some people have permanently damaged their eyes after using an eyepiece solar filter.

An excellent homemade sun filter for a telescope will show the sun’s disk in different colors. For example, it may offer you a halo of red and blue or a sunspot.

You can also see the Chromosphere. The Chromosphere is the region of the sun’s atmosphere between the photosphere and the corona. The Chromosphere may contain plasma and prominences.


The sun is a seething, hot, and violent place. Its photosphere contains an enormous number of fascinating features. Unfortunately, the light from the photosphere, the outermost layer of the sun’s atmosphere, escapes into space, making a solar filter for telescopes vital.

This powerful energy makes it dangerous to observe extensive solar features with your naked eye. However, a safe solar viewing telescope filter can let you view the sun’s photosphere through the optical path, providing your eyes with extra precautions.

You can choose from several filters for your solar telescopes, including the front-mounted H-alpha filter, hydrogen-alpha filters, and white-light filters.

All these filters will reduce the intensity of the light reaching your telescope. In addition to reducing the sun’s heat, they let you safely observe the photosphere, making a solar filter for a telescope worth it.

A white-light solar filter lets you see the sun’s photosphere at visible wavelengths. This filter can be a helpful way to observe the sun’s rotation and planetary transits across its face. It can also reveal solar faculae, granules, and sunspots.

This filter will help you view the photosphere at low magnification so that you can look closely at the groups of sunspots in the sun’s center.

To safely observe the sun, you must ensure that your telescope uses a solar filter. These filters can give you amazing views of the sun’s disk during a partial-phase solar eclipse.

During a total solar eclipse, a DIY solar filter telescope can offer stunning views of the disk during transits of inner planets.



No, an ND filter is not the same as a solar filter. An ND filter is an optical filter that reduces the amount of light that passes through it. A solar filter is a specialized filter designed to block out harmful ultraviolet and infrared light from the sun.


There are a few ways that you can see the sun without a solar filter. One way is to use a type of telescope called a hydrogen-alpha telescope. These telescopes allow you to see the sun in a different light and don’t require a solar filter. Another way to see the sun without a solar filter is to use unique sunglasses for looking at the sun. These sunglasses will protect your eyes from the harmful rays of the sun.

Summary: DIY Solar Filter Telescope

A solar filter telescope is a great way to view the sun safely. Following the simple instructions above, you can make your solar filter telescope at home.

A solar filter telescope allows you to view the sun safely. Solar filters block more than 99.999% of the sun’s light and harmful UV and IR radiation. It is essential to remember always to use a properly designed and installed filter when looking directly at the sun.

It is essential to test your solar filter before using it to make sure that it is secure and will not damage your telescope.

Remember, always use caution when looking at the sun and only look directly at the sun through a telescope with a proper solar filter.

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.