With the recent sunny warm weather, clear daytime skies and heading into Summer with the Sun high in the sky, Solar astronomy becomes a popular “astro activity”.
To observe and image the Sun SAFELY (and that is very important!) we wanted to give you an overview of some popular white-light Solar related products from Baader Planetarium. In white light you can see/image Sun-spots and Sun-spot groups, Solar granulation and Faculae. To find out more about Solar features that can be seen in white light see this article for example.
Baader AstroSolar film
Probably one of Baader’s most popular products, these front end/objective end filters are available in two optical densities and various sizes:
- ND3.8 is for imaging use only and available in 20cmx30cm sheets.
- ND5.0 for both visual and imaging purposes. Available in (near A4 size) 20x30cm sheets (the most popular), an economical sized 14cmx15.5cm sheet, 100cm x 50cm roll and a large 117cmx117cm sheet for large aperture telescopes.
With these solar filters it is up to you to make your own filter holder. However this is not complicated. There are plenty of ideas you can grab “off the net” but Baader also offer an instruction sheet on how to make a filter holder. You can download it here.
These Solar Viewers use AstroSolar® Silver/Gold Film which has been specially developed for (zero magnification) safe visual solar observation! The film gives 100% UV-protection, 100% IR-protection, and reduces the Solar light intensity by 99.999%. This film is only being used for use with Baader’s Solar Viewers. The film is mounted in a strong card glasses-type frame – so these are solar viewers that you “wear”! These are often used for viewing the lead up to the totality phase of a total solar eclipse, but they can also be used for non-eclipse purposes such as viewing very large sunspots or sunspot groups on the Sun should they arise.
Ready-made Solar filters for Telescopes, Binoculars, Camera lenses, spotting scopes and telescopes
These ready made filters are for use with a wide variety of optical instruments. Baader AstroSolar film is already mounted in unique filter cells which have elongated slots and rubber-coated bolts so the filter unit can be fitted onto a range of different telescope tube sizes**. There are four versions of the ready made filters available:
- ASBF – AstroSolar filter for Binoculars and camera lenses from 50mm up to 100mm in aperture. These filters are “D”-shaped so that when they are used with binoculars the “flat part” of the filter cell allows the bridge of the binocular to close inwards as much as possible (see image below).
- ASSF – AstroSolar filter for Spotting scopes, small telescopes and camera lenses from 50mm up to 150mm in aperture
- ASTF – for high quality Telescopes from 80mm up to 280mm in aperture
- BDSF – uses ND3.8 version of solar film for imaging (NOT visual) purposes and the packaging, with additional stick-on warning labels clearly shows that the filter is for imaging purposes only. As with the ASTF range, the BDSF filters can be used with telescopes from 80mm to 280mm in aperture.
** Please note: For any of the ready-made filters, the correct filter for your optical equipment will also depend on the outside and/or inside diameter of your telescope tube wall. For more information:-
- Click here to download Baader’s information sheet for the clamping range for the filters
- Use the useful AstroSolar 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.
ONLY to be used in conjunction with Baader’s AstroSolar film, ready-made filters, or Herschel Wedge – and not on it’s own – this green coloured filter has a 10nm bandpass with a central wavelength of 540nm, which is near that of the peak emission wavelength of the Sun. The filter reduces the effect of atmospheric turbulence and enhances contrast of Solar features. It is available in 1.25″ and 2″ sizes
Looking like a “beefy” diagonal at first glance, a Herschel prism is used instead of a mirror (as in a mirrored diagonal), and gives great sharp views of the Sun in white light. The unit utilises a heat absorbing Ceramic tile (like tiles used on the Space Shuttle) on the rear of the unit where the exiting beam from the Herschel prism is directed, but remains cool. The Ceramic tile also acts as a “Solar-projection screen” so allows finding the Sun with your telescope easier too!
The Baader Herschel Prism uses Baader’s T-2 system for attaching telescope- and eyepiece-side accessories. A 2″ nosepiece (telescope-side) and Baader’s 2″ Click-Lock (eyepiece-side) are supplied as standard.
There are two models available for the Baader Safety Cool Ceramic Herschel Prism:
- Visual – includes 2″ ND3.0 and 2″ Solar Continuum filter which are already pre-mounted above/after the Herschel wedge
- Photographic – has four 2″ filters: ND0.6, ND0.9, ND1.8 and ND3.0 and Solar Continuum (ND3.0 and Solar Continuum pre-mounted as above)
Both versions come with a well made storage and carry case to keep the Herschel wedge and filters safe.
The pack features a double stacked Calcium K-line filter with a bandpass of 390-398nm, which allows through the Ca-K (393.37nm) and Ca-H (396.85nm) lines, and a 200mmx290mm sheet of ND3.8 AstroSolar film. The Ca-K light is emitted from a region about 500km or so above the Solar photosphere. Please note: This filter is for imaging purposes only.
Looking at the Sun through a telescope (with proper safety equipment being used of course) is often difficult due to the bright daytime conditions. These Solar shades are used to shade the eyepiece or camera (DSLR) screen from direct sunlight making observation or imaging easier. The Solar shades are available with holes that will connect to T-2, 2″ and M68 accessories.
We will look at some more Baader Solar-related products as well as looking at some of those described above in more detail in future blogs soon. See more of the Baader Solar Astronomy products here.