Don’t be scared of viewing the eclipse!
A total solar eclipse is a spectacular event that you absolutely need to see. I want to make sure you see it safely. You are going to be looking at the Sun as the moon slides in front of it. Your vision is at risk whenever you look at the Sun, which is why safety is important.
Sun safety can be scary (I even made the page orange) but with the right knowledge and filters, it is perfectly safe. Fortunately, everything you need, including eclipse glasses, is included with the Eclipse Guide and Eclipse Kits available on this website.
Viewing the Sun requires blocking out 99.99% of the light. That includes not just the visible light, but also the invisible, including ultra-violet (UV) light and infrared (IR) light. UV light is what gives your skin a tan when you lay out in the Sun. IR light is the heat you feel. Without blocking these types of light, viewing the Sun would cause long-term eye damage. Fortunately, there are inexpensive solutions in the form of certified eclipse glasses and white light solar filters that make viewing an eclipse safe and accessible.
Solar eclipse glasses and similar specialty filters (including those designed for telescopes or binoculars for solar observing) block 99.99% of the light passing through them. This includes UV and IR light, which your eyes can’t see, but is equally important to block out. Since they block so much light, eclipse glasses appear completely black when you look through them. The Sun is basically the only thing you’ll be able to see.
In all cases, always follow the manufacturer’s instructions that accompany the eclipse glasses. Eclipse glasses are intended for looking at the Sun directly with no magnification. Never attempt to look through a telescope or binoculars. Never try to look through an unfiltered telescope or binoculars at the Sun! The strongly focused sunlight at the eyepiece can burn your eye, and will melt or burn eclipse glasses. To be used safely, telescopes, cameras, and binoculars need their own white light filters, discussed below.
Commonly available commercially-manufactured eclipse glasses are made with plastic or cardboard frames, and typically use a specialized mylar-like material for the lenses that has been tested and certified to be safe. Look for an ISO or CE certification mark on the glasses before use.
When you get a pair of eclipse glasses, check them carefully to make sure there aren't any holes or missing filter material. Protect the lenses of your eclipse glasses from scratches and other damage, and they can be reused over and over. If the mylar becomes damaged, destroy and dispose of the glasses.
Eclipse glasses can be used to look at the Sun at any time, not just during an eclipse. However, most of the time, all you will see is a bright ball of light.
#14 Welder’s Glass
The one other optical material besides certified eclipse glasses that can be safely used to look at the Sun is #14 welder’s glass, which can generally be ordered from a welding supply shop.
White Light Filters for Cameras, Telescopes, and Binoculars
If you would like to observe the eclipse with a telescope, binoculars, or a camera, don’t get sucked into money saving “tricks” to block the light – spend a little bit of money on certified solar filters, and be safe. Most solar filters for telescopes or binoculars are designed to be placed over the objective – the end pointed at what you are viewing - not at the eyepiece.
In years past, some cheap telescopes came with a solar filter that could be threaded onto the eyepiece. Never use these eyepiece solar filters. Heat buildup can cause them to crack, leading to potential eye damage. Throw them in the trash! If you happen to be looking through the eyepiece when a filter like that fails, severe eye damage could occur. The only type of safe solar filter that can be used on the eyepiece end of a telescope (and then only on refractor telescopes) is known as a Herschel wedge, which start at around $250. Don’t worry though – high quality and safe white light solar filters can be had for less than $50.
For a list of known safe filters for cameras, telescopes, and binoculars, please visit our website at http://eclipsekit.com/solarfilters for how to size a filter, and where to order.
Always use a solar filter!
Proper filters must be used during all of the partial phases of a total solar eclipse (even looking at the Sun when it’s as much as 99 percent eclipsed without a filter is unsafe). A filter must also be used at all times during an annular or partial solar eclipse. The only time it is safe to look at the Sun naked-eye is during the very brief few minutes of totality. For more on eclipse viewing safety, see https://eclipse2017.nasa.gov/safety
The information on this page is taken from the Eclipse Safety section of the Eclipse Kit Observer's Guide to the August 21, 2017 North America Total Solar Eclipse.