Using a Herschel prism requires a good understanding of the risks involved in solar observation. For beginners, we recommend standard solar filters instead.
A Herschel prism offers particularly high resolution for solar observation and photography.
- Can only be used with refracting telescopes. For reflecting telescopes, please use solar filters in front of the objective instead!
- Use with caution! Not suitable for inexpensive telescopes with plastic parts inside! These could melt or even smoulder if the telescope is not aligned precisely with the sun!
- Always supervise telescopes that are aligned with the sun using a Herschel prism !
96% of the sunlight passes straight through the prism and hits the ceramic disc. This converts the light into heat. Therefore:
- 2" prism usable up to 150 mm lens diameter
- 1.25" prism up to 120 mm.
Telescopes with a larger aperture can of course be dimmed.
Advantages of Omegon Tess-Herschel prisms
- The diffuse spot on the ceramic disc is ideal for aligning the telescope precisely with the Sun
- Built-in polarisation filter – adjustable brightness: shorter exposure times, observation even in light cloud cover with decent contrast
- Built-in neutral density filter: Safe observation, but the image must still be dimmed well!
Reliable connection of eyepieces and cameras:
- 2" prism has twist lock closure
- 1.25" prism has T2 thread for cameras and ring clamp
Our expert comment:
Tip: Remove the finder scope from the telescope during solar observation to prevent accidental or deliberate looking through the finder. Instead, you can mount the accessories Euro EMC Sonnensucher S 074, Oberteil. With the Herschel prism, the illuminated dot on the ceramic plate serves as a solar finder.
Herschel wedges are designed for the observation of the sun with refractors.
Functionality: About 95% of the sunlight is blocked out, the rest is further attenuated by a permanently installed ND3.0 grey filter. As the Herschel wedge polarises the transmitted sunlight, a variable polarising filter can then be used to reduce the sunlight to the desired level. The difference to objective solar filters is that the filtering takes place just before the eyepiece or camera. As a rule, the contrast and sharpness of the solar image is higher with a Herschel wedge than with an objective solar filter.
The advantages:
- Particularly high-quality surfaces for very good contrast
- Completely closed housing with integrated light trap, no escaping stray light - therefore particularly safe
- the absolutely necessary ND3.0 filter is already permanently installed
Can only be used with refractors up to 150mm aperture: As the full solar energy enters the telescope and the filtering only takes place just before the focal plane, we only recommend refractors for working with Herschel wedges. The refractor must also not have a rear corrector lens. Optical elements such as corrector lenses or the secondary mirror of a reflector telescope would be heated so much by the concentrated solar energy that damage cannot be ruled out.
