1.25" T2 Herschel prism with ND3 filter

Herschel prisms (also known as Herschel wedges or sun prisms) enable observation and photography of the sun in white light. Herschel prisms are designed for use with refracting telescopes. These telescopes must not have a built-in corrector.

The Brewster angle used in this Herschel prism allows for almost 100% polarization. With a polarizing filter and the ND3 neutral filter, you can achieve optimal brightness adjustment for the best possible perception of granulation and structures around sunspots (penumbra).

Since the light from the Herschel prism is polarised, a simple polarising filter screwed into the eyepiece or camera adapter is sufficient. You can easily adjust the brightness by turning the eyepiece or camera adapter.

How do you use the Herschel prism?

• The polarisation filter and the ND3 filter are screwed into the eyepiece or camera adapter.
• The brightness is adjusted by turning the eyepiece or camera adapter.
• The order is always: telescope, Herschel prism, filter, eyepiece or camera – the filters must not be inserted between the telescope and the Herschel prism.

An ND3 grey filter is essential when working with a Herschel prism. For visual observation, you will also need a polarising filter.