The APM 2" Hersche Wedge is designed for solar white light imaging and white light visual observing. The APM Wedge comes with a built in ND3 filter which allows perfectly safe imaging or visual observing of the Sun. ABove the ND3 is a Polarising filter which can be rotated. The function of the Herschel prism is based on the principle that only a small part (approx. 5%) of the incident light is used for the actual observation. The part, which is incomparably larger and also energetic, is guided through the housing and forms a focal point outside the prism. Even far behind this focal point, the light concentration is still very intense, so that (with older prisms) caution had to be exercised, so that no inexperienced observer would accidentally look into the output light beam. The APM Herschel Wedge is equipped with the ceramic light trap, multicoated integrated ND3 filter and (removable) multicoated polarizing filter. The sun can therefore be safely observed.
Image brightness can be adjusted by twisting of the polarizing filter. This is done by rotating the 2" eyepiece holder from outside.
The APM 2" Wedge has a clear optical aperture of 46mm. Use of a Herschel prism (in comparison with solar film) offers better quality. The image has more contrast, is sharper and allows higher magnification. Other features of the wedge include a 'Fastlock' clamp for quick and secure mounting of eyepieces. The rear of the Wedge also displays the sun and can be used as a simple solar finder. The Wedge is supplied with a cut foam case which has room for additional accessories.
Note: Herschel Wedges are only suitable for use with refracting telescopes and should not be used with reflecting telescopes .
