Herschel prisms (also Herschel wedges or prisms sun called) allow the observation and photography of the sun in white light. Herschel prisms are intended for use on refractor telescopes. These telescopes may have no built-corrector.
The Brewster angle as used in this Herschel prism allows a polarization of nearly 100%. In order to achieve a polarization filter and the ND3-neutral filter optimal brightness adjustment for the best possible perception of the granulation and the structures around sunspots (Penumbra).
Since the light of the Herschel prism is polarized, it is sufficient a simple polarization filter, which is screwed into the eyepiece or camera adapter. You reach the brightness change simply by turning the eyepiece or the camera adapter.
How to use the Herschel prism?
- The polarization filter and the filter ND3 be screwed into the eyepiece or in the camera adapter.
- The brightness is adjusted by rotating the eyepiece or camera adapter.
- The order is always: telescope, Herschel prism, filter, eyepiece or camera - the filter may not be used between the telescope and the Herschel prism.
For working with a Herschel prism ND3-gray filter is essential. For the visual observation Furthermore, you need a polarizing filter.