Warning!

*** Warning - Looking at the Sun is dangerous ! ***


The Danger

Direct viewing of the Sun without a filter or viewer specifically designed for the purpose is dangerous and can result in eye damage or blindness. Use this table to see what is and is not safe practice.

Safe

Unsafe

SafeAn eclipse viewer certified for visual use - make sure that it is undamaged and has no holes in it. Also make sure that you put it to your eyes before you turn to face the Sun!

SafeA welders' glass or black polymer filter certified for visual use (rated #14 or higher, corresponding to 1 part in 100,000 of light transmitted). Must be fitted to the front of any telescope or binoculars.

SafeA metal coated glass or mylar filter, certified for visual use. Must be fitted to the front of any telescope or binoculars.

SafeThe LCD screen / viewfinder of a digital camera, but not the direct optical viewfinder - if the sun is too bright it will damage the camera but at least your eyesight remains intact!

SafeA safe projection method for viewing the Sun indirectly.

SafeSpecialised astronomical equipment (e.g. Hydrogen Alpha filter, Herschel wedge) used according to manufacturer's instructions.

SafeFully exposed and developed black & white film containing silver, but not colour or chromogenic B&W film. Safe but not recommended as too much possibility of a mistake.

 UnsafeLooking with the naked eye unprotected or with sunglasses or with any filter not rated for visual use.

 UnsafeUsing any optical equipment (for example, binoculars, telescope, camera with optical viewfinder) unprotected or with any filter not rated for visual use.

UnsafeAny filter fitted to the rear of a telescope or binoculars, unless it forms the second line of defence in a two part system (for example, Hydrogen Alpha). The dark filters supplied with some small telescopes to screw into the eyepiece are definitely not safe owing to the risk of cracking in the extreme heat.

UnsafeHome made shields (for example, CDs, smoked glass, crisp / chip packets, exposed colour or chromogenic B/W film etc) - these appear to reduce the intensity of the Sun to a comfortable level but transmit dangerous amounts of invisible infra-red or ultra-violet radiation that can cause retinal burns. May be suitable for photographic use in the absence of a proper filter, but you must not look through the viewfinder with any of these attached.

UnsafePhotographic neutral density or polarising filters are OK for photographic use but are not safe visually - same reasons as above. Again, do not look through the viewfinder!

For further information on safety see Safety! at this Transit of Venus site or the Observing page of this Transit of Venus 2004 site.

It is relatively safe to look at the Sun directly only is when it is dimmed by shining through murk close to the horizon or through thick fog / smog. Even then, look for only a few moments and only if it is comfortable to do so.

During solar eclipses the normal rules apply for all partial or annular phases. Only during the moment of totality is it safe to look without any filter - indeed this it how it should be done for any filter will spoil the amazing view.


How I get pictures of the Sun

I use any of three filters for safe viewing and photographing the Sun...

  • Welders Glass: a solar eclipse viewer of no. 14 welders glass reduces the brightness of the Sun by a factor of 100,000. The reduction in intensity is more or less even across the spectrum, so gives the Sun a natural appearance. This filter is not large enough to cover a telescope but is perfect for using in front of the camera, held in place with an A-series Cokin filter holder. I used it to good effect on the partial phases of the Australian Outback eclipse of December 2002.
A few minutes before totality, 4 Dec 2002

  • Orion White Light Filter: this filter is suitable for my 8cm Helios refractor and has a metal coating to reduce the light intensity across the spectrum. The Sun's appearance is similar to looking through the welders' glass, though it has a slight brown tinge. It is the perfect way to view sunspots and planetary transits.

Filter manufactured by Orion (www.telescope.com)

Sunspots seen in white light

  • Coronado Hydrogen Alpha Filter: this two-part filter, with a front element of 4cm clear diameter, is also suitable for the Helios. It also reduces the light by a factor of around 100,000 by completely blocking all but a tiny part of the spectrum corresponding to the Lyman Alpha emission of ionized hydrogen. This gives the Sun a very unnatural red appearance (or yellow when over-exposed with the Philips ToUCam webcam), but reveals a wealth of detail not visible in white light. Apart from during a total eclipse, this is the only way to see flares and prominences in the Sun's atmosphere.

Filter manufactured by Coronado (www.coronadofilters.com)

The same sunspot group in Hydrogen Alpha light


 

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