2" BBHS® Prism – Adjustable Star Diagonal

BBHS^® provieds a much broader spectral range with 98-99% reflexion from just above 390nm to 2000nm, and it maintains high reflectivity even with varying viewing angles – the silver layer produces no stray light whatsoever. A trained eye will especially see a greater colour range when using short focal length APO refractors. Particularly in planetary observation at the highest magnifications, a noticeable increase in colour intensity can be easily observed compared to all previous coatings. Additionally, a clear increase in contrast is noticeable due to the absence of any stray light. Together with the CNC-milled aluminium housings, this ensures extremely fast temperature adaptation and image stability. As a general guideline, prisms are recommended for telescopes with a focal ratio of about f/6 to f/7 or slower, while  BBHS^® mirrors are preferable for faster optical systems.

In addition to the sealed BBHS^®rear-surface coating, the prisms feature the proven Phantom Coating^® Group anti-reflection treatment.

The precisely fitting 2" ClickLock^® eyepiece clamp securely holds even heavy accessories with a simple 20° twist. By cleverly using leverage, the clamping force is multiplied many times. The inserted accessory is held on three sides, similar to a quick-release chuck, preventing any tilting movement. Every eyepiece or measuring device is automatically aligned parallel to the optical axis – even in the case of diameter tolerances.

The BBHS^® Prism is mounted in a CNC-machined aluminium housing and rests stress-free on an adjustable cradle. Just like a high-quality refractor objective, the prism can also be collimated. This allows the realisation of fully adjustable systems, for example for the construction of binocular telescopes. As with a premium refractor, you will not need to change the collimation during normal use: the 3-point alignment is set at our factory so that the image shows no noticeable rotation around its centre when the star diagonal is rotated by 180° in a correctly aligned eyepiece clamp. Optical and mechanical axes are perfectly matched on our optical test benches. Therefore, make sure to rule out all other potential sources of error – such as a tilted focuser – before adjusting the collimation.

When a BBHS^®Prism leaves our factory, the optical and mechanical axes are aligned rotationally symmetrically with each other on the optical bench. Please note that once the collimation is changed, the warranty on the factory collimation of the BBHS^® prism becomes void. All other warranty coverage remains unaffected.  Should you notice immediately after purchase that the optical axis is not correct, please contact the dealer from whom you bought the device without delay.