We’re now just under a month away from Mercury’s transit across the face of our Sun on November 11th – see here for more details on this celestial event.
To view or image this transit safely, Baader Planetarium offer a range of “ready made” Solar filters that use their AstroSolar ND3.8 (photographic only) and ND5.0 (visual and photographic) film to fit onto a range of different optical equipment. There are four “versions” of the ready-made filters available and each filter comes with 3 rubberised centring (clamping) bolts, safety straps with adhesive pads, screws, washers and instruction booklet.
- 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 only (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 200mm+ in aperture.

Baader BDSF Solar filter for imaging use only
To determine what size filter you need you will find the table below useful. You can download the table in PDF format here.

Baader AstroSolar Clamping Range
We wish you clear skies for this transit event!