The June 10th Solar Eclipse

In just under a month, an annular Solar eclipse will take place on the morning of Thursday June 10th. An annular eclipse occurs when the Moon passes between the Earth and the Sun but the Moon's apparent diameter is smaller than that of the Sun's due to the Moon's orbit being elliptical and it being further away from our Earth (at/near apogee) at that time. This leads to the outer parts of the Solar disc being "exposed" in an annulus or ring - often called "ring of fire".

For those lucky enough to live in north-east Canada, western Greenland and far eastern Russia, will get to see the annular phase event which will last for a maximum of 3m 51s over north west Greenland. For people living in northern Europe including, Germany, UK, Portugal and Spain a partial eclipse will be visible. The amount of obscured Sun will vary depending on your location and below are some approximate values of this amount for a selection of locations:

10th June 2021 Annular (red) and partial (blue/grey) eclipse path. From

  • Germany (north / south): ~17% / ~6%
  • Austria: ~4%
  • Czech Republic: ~8%
  • France (north / south): ~17% / ~3%
  • Iceland: ~60%
  • Norway (Oslo): ~31%
  • Spain (north / south): ~8% / ~1%
  • Sweden (Stockholm / Tromso): ~26% / ~51%
  • Switzerland: ~6%
  • UK (north / south) ~36% / ~20%

The image above right shows the path of the eclipse. The dark orange shows the land regions that will see the annular eclipse with the light-orange and yellow shading being the land areas experiencing the partial eclipse. For more details including an animation of the eclipse path see website. Also visit NASA's Solar Eclipse website for an interactive map where you can see locations, times of the eclipse and amount of the Sun obscured.

It is most important to mention that when it comes to the Sun safety is paramount: Never directly look at an annular or partially eclipsed Sun as such an event still requires the use of appropriate safety equipment such as our AstroSolar® OD5.0 film or our Safety Herschel Prism.

White light intensity view of the Sun from the GONG website

At the moment the Sun is coming out of Solar minimum so hopefully when its "eclipse time" it's surface will have some activity in the form of Sunspots or Sunspot groups and faculae too. To see how active the Sun is at the moment there is a very useful resource in the form of the National Solar Observatory's GONG website. GONG stands for Global Oscillation Network Group and it is a network of six sensitive imaging systems located around the Earth to obtain nearly continuous observations of the Sun's "five-minute" oscillations, or pulsations. You can see the range of near real-time Solar images here with the white-light views on this page from the different sites.

Pin hole camera obscura image showing the partially eclipsed Sun

A simple and no-cost way of seeing the eclipse is by using a simple camera obscura. This simply consists of two pieces of card, or a cardboard box (e.g. shoe box), with the skyward end of the unit having a pin-hole (or holes) punched into it and the Sun's image is projected onto the card opposite. A simple guide of how to make one easily can be found on our website. The image to the right shows the result of such a set up using two A4 pieces of card from the total Solar eclipse in the USA in 2017 where holes were made in the skyward "shadow maker" cardboard sheet to show the location and date of the event. A crescent partially eclipsed Sun is easily seen.

To view and image the eclipse filters are most often used and we offer a range for different applications.

Baader AstroSolar Eclipse Glasses

Solar Viewer AstroSolar® Silver/Gold: Sometimes referred to as "Eclipse Glasses", these are the simplest and easiest way to observe a Solar eclipse. These viewers use our (made in Germany) AstroSolar® Silver/Gold Safe film which reduce the sun light intensity by 99,999% and give 100% UV- and IR-protection to safely protect your eyes for visual solar observation. The Solar film is mounted in a strong card sunglasses-type frame – so these are solar viewers that you wear like sunglasses. Apart from an eclipse they can also be used for viewing very large sunspots or sunspot groups should they develop.

Baader AstroSolar film

Baader Digital OD 3.8 Solar film - for imaging use ONLY

Baader OD 5.0 Astrosolar film for safe visual and photographic use

One of our most popular products, these very high quality front end/objective end film filters are available in two optical densities and various sizes:

  • AstroSolar® OD 3.8 Photo Film: is for imaging use only and currently available in 20cmx30cm sheets.
  • AstroSolar® Safety Film OD 5.0: Can be used for both safe visual and imaging purposes. These are currently available in sheets of 14x15.5cm, 20x29cm (~A4 size - our most popular size) and 117cm x 117cm giant sizes.

With these Solar filters it is up to you to make your own filter holder. However this is not complicated and you can find a useful guide here and some additional information on our AstroSolar website.

Baader ready-made AstroSolar® filters

Ready-made AstroSolar filters

These ready-to-use filters use our high quality OD 5.0 AstroSolar® Safety Film (OD 3.8 for the Digital Solar filter - see below) for the but are pre-mounted stress-free in a unique aluminium cell which have elongated slots and rubber-coated bolts so the filter unit can be fitted and securely clamped onto a range of different telescope tube sizes. Three safety Velcro safety straps and full instructions are included.

For any of these ready-made filters, the correct filter size for your optical equipment will depend on the outside and/or inside diameter of your telescope tube wall and for more information:

Clamping range of our ready-made Solar filters

  • Click here to download Baader's information sheet for the clamping range for these filters (seeimage opposite too) for newtonians, refractors/camera lenses and compound instruments.
  • Use our useful Solar Filter Finder Tool which allows you to simply select what telescope/lens etc you have and the appropriate filter model will be displayed: see here to use the Filter tool.

Our ready-made filters are available in four versions:

ASTF: AstroSolar Telescope Filter - for use with telescopes and large telephoto lenses from 80mm up to 280mm.


ASSF: AstroSolar Spottingscope Filter - for small telescopes, spotting scopes and camera lenses with apertures from 50mm to 150mm. The image below left shows a test set up for the 2017 American eclipse with a small refractor telescope (left-side) having an ASSF on its objective end and an ASBF attached to a DSLR telephoto lens (right-side).

ASSF (left) and ASBG (right) on a pre-eclipse trip test run

Below is an image of a partially eclipsed Sun taken through an ASSF filter with a DSLR and a telephoto lens. Sunspots and faculae can be seen. The image to its right is the same image but simply colorised.

Partially eclipsed Sun through an ASSF filter

Simple colorized image of the image

Baader ASBF filters attached to binoculars mounted on a 10Micron BM-100 binocular mount

ASBF: AstroSolar Binocular Filter - for use with binoculars (or small telescopes and camera lenses) from 50mm to 100mm in aperture. The filter holders are "D" shaped so that the two binocular objectives can be moved close together for comfortable viewing. The ASBF filters can also be used on their own on a small telescope or with e.g. two camera lenses or a small telescope and camera lens mounted side-by-side and positioned close together. The filters are supplied as one unit only, so for binocular use you will need to purcahse two of the ASBF filters. The image to the right shows a pair of ASBF models attached to a large pair of binoculars that are mounted on a 10Micron Leonardo BM-100 Bino Mount.

With the above OD 5.0 ASTF, ASSF, ASBF ready-made filters and OD 5.0 AstroSolar film you can use our Solar Continuum filter and Baader Solar Continuum Filter 1¼" (double stacked) (#2458392 , € 180,-) which enhances contrast and reduces the effect of atmospheric turbulence. Our 2" Cool-Ceramic Safety Herschel Prism which is available in a visual and photographic version, also allows for safe white light Solar observation and imaging with refactors up to ~150mm.

Baader Digital Solar Filter (BDSF) showing the prominent warning sign that it is for imaging use only

BDSF: Baader Digital Solar Filter - for telescopes and lenses from 80mm to 280mm in aperture. As with the OD 3.8 AstroSolar film this is for high speed digital imaging only and NOT suitable for visual solar observation. A warning label on the front of the filter warns the user that the filter is not for visual use.


Eclipse Imaging

Please remember that appropriate safety filters must be used when imaging the eclipse (as we have outlined above).

For those that want to image the eclipse there are many ways to do this. The exact settings on your camera will depend on your particular equipment and set up, and it is best to do some practice runs prior to the event. However low ISO and fast shutter speeds are usually used. You can take photos simply and easily with your mobile phone or a camera of the pin-hole camera obscura projected Solar image mentioned earlier.

If you want to image the eclipse through a telescope and capture some fine Solar surface detail and granulation you can use our Baader Solar Continuum Filter 1¼" (double stacked) (#2458392 , € 180,-) which also comes with a A4-sized AstroSolar® Photo Film OD 3.8. For those wanting something a little different when imaging, our Baader K-Line Filter 1¼" (double stacked) (#2458355 , € 334,-) will let you image in blue Calcium-K light showing the Sun's chromospheric details.

Afocal photography can be done with binoculars, spotting scopes or telescopes using our Microstage II Digiscoping Adapter (#2450330 , € 55,-) which accommodates cameras up to ~1.5kg and features a swivel arm that allows you to easily swap between a "photo mode" and then go back to visual observing. If you want to use your mobile phone, there is the Celestron NexYZ Universal 3 axis Smartphone Adapter for easy smartphone camera placement over your eyepiece.

Morpheus range of eyepieces. Can also be used for projection imaging too.

Our Hyperion and Morpheus range of eyepieces allow you to observe the event with your telescope (with an appropriate safety filter) and with the many adapters that are available for them, allow afocal and/or eyepiece projection imaging using DSLR, Mirrorless/MILC, camcorders and astronomical Solar system imagers too. You can find out more on how you can use these eyepieces for imaging in our Hyperion application example brochure, Morpheus Visual and Photography guide and our digiscoping guide.

Please always remember that a suitable safety solar filter must always be used if observing or imaging our Sun!

We wish you clear skies for this event and we look forward to seeing your results!



About the author: Lee Sproats

Lee Sproats

Dr. Lee Sproats has been interested in astronomy since watching Star Wars in 1977 and has appeared on the UK Sky at Night TV programme. He then went on to study Astronomy where he obtained a degree and then a PhD in the subject at University College London/Mullard Space Science Laboratory. He has worked in Australia in radio astronomy and used optical/infrared telescopes on Hawaii and La Palma and Lowell and Kitt Peak observatories in the USA. After working for the University of Surrey to promote the use of computers for teaching in UK higher education and then as an IT trainer for a stock market company, he went on to work for Greenwich Observatory Ltd where he ran their northern branch and then worked for David Hinds Ltd dealing with our and Celestron products. He is often involved in flight excursions that take passengers to observe the northern lights, has led trips to see the great USA 2017 eclipse near Hopkinsville and was lead astronomer onboard a specially chartered 737 to view the 2015 total solar eclipse at 38,000ft. Lee`s astronomical interests include Lunar observing, astrophotography, photometry and pro-am collaborations.

Since David Hinds stopped operation in December 2020, Dr. Sproats works for Baader Planetarium as our UK representative/consultant and is responsible for looking after our UK/Eire dealers, dealing with Baader Planetarium/PlaneWave/10Micron product support, writing articles and also is involved in our large telescope and observatory instrumentation projects.

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