A special presion polished and coated Baader ND=3.0 filter is permanently pre-installed within the wedge housing no objective filter is needed - and a 2" Solar Continuum filter further enhances contrast and image stability. The translucent cool-ceramic back plate acts as a fine aiming device.
Photographic Version with four neutral density filters 0.6/0.9/1.8/3.0 and 2" Solar Continuum filter for variable brightness control.
The Herschel Wedge is only recommended for use with refracting telescopes, NOT Schmidt-Cassegrain, Maksutov, or any other Reflecting Telescopes. This is a professional-quality white light (not H-Alpha) solar filtration system, whose basic design concept has existed for almost as long as the telescope itself. Like glass or mylar film objective solar filters, it is completely safe if used properly and common sense precautions always observed.
Similar in length to any 2" diagonal, the Baader Cool-Ceramic Safety Herschel Prism requires more back-focus than a 1.25" accessory. The optical path length of the Herschel is approximately 128mm, as measured from it's front face to the top of the 2" eyepiece holder. Since most 2" eyepieces have their field stops well below the main eyepiece body, most telescopes will need less than 128mm of back focus to accommodate the Herschel. Most telescopes with 2" focusers will have no problem providing this amount of back-focus (in-travel). However, some telescopes provide limited back-focus that may require a shorter path length for some eyepieces. For these scopes the path length of the Herschel may be reduced to 108mm for 1.25" eyepieces by the attachment of a T2-27 adapter and T2-08 1.25" Clicklock eyepiece clamp.