APM Ceramic Safety 2" Herschel prism with APM Fast-Lock Eyepiece Adapter

APM Ceramic Safety 2" Herschel Prism with APM Fast-Lock Eyepiece Adapter

For solar white light imaging and white light visual observing. The APM White Light Wedge comes with a built in ND3 filter which allows perfectly safe imaging or visual observing of the Sun.

The function of the Herschel prism (also called Herschel wedge) is based on the principle that only a small part (approx. 5%) of the incident light is used for the actual observation. The much larger and also energy-rich part (95%) is passed 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 to prevent inexperienced observers from looking into the output light beam by mistake.

The APM Herschel prism is equipped with the ceramic light trap, an integrated multicoated ND3 filter and (removable) multicoated polarizing filter. The sun can be safely observed with the APM Herschel prism.

The image brightness can be adjusted by twisting of the 2" polarizing filter by rotating the 2" eyepiece holder from outside. Thus the Herschel prism can be used both visually and also photographically same good!

The special features of the APM Herschel wedge:

screwed-on, but also removable top polarizing filter in the 2" receptacle

rotating the 2" polarizing filter by a lever from the outside

APM Fastlock eyepiece clamp

The clear optical aperture is 46 mm!

The use of the Herschel prism (in comparison with film filters) for solar observation is not only more safe, but also of better quality. The image has more contrast, more sharpness, and allows higher magnification.

Important note: The application of the Herschel prism is only suitable for refractors. Please also note that Herschel prisms must not be used on Petzval systems or other telescopes that have glass in the optical path near the focal point. Multi-lens systems do not pose a problem as long as all optics are only at the front of the objective.

Instructions

APM provides instructions, you can download the PDF here.