It is screwed into the front of the eyepiece - the front part of the filter can be rotated to steplessly adjust the brightness.
The ideal filter for observing the Sun and Moon and for enhancing contrast for planetary observing. The brightness can be adjusted to suit the magnification used.
- with screw-in mount
- rotating, front filter mount
Caution!: only to be used as an additional filter when solar observing, for example together with a Herschel prism or a foil solar filter!
