What is the main advantage of the Baader T-2 BBHS Mirror Diagonal's coating?
BBHS (Broad Band Hard Silver) gives 98-99% reflection from slightly above 390nm to 2000nm, no drop in reflectivity at different viewing angles and no stray light from the silver coating, which is ageing-stabilised by a protective hard dielectric coating. The trained eye sees more colours, especially with short focal length APO refractors.
How do I attach a 1.25" eyepiece to the Baader T-2 BBHS Diagonal?
Through a T-2 eyepiece holder from Baader's T-2 system, which attaches to the diagonal's female T-2 eyepiece-side connection.
What does Baader say about planetary observing with BBHS?
When observing planets at the highest magnification, a conspicuous colour intensification can be detected, and contrast increases noticeably because the silver coating produces no stray light.
Can the UFC filter changer be used with this diagonal?
Yes. All Baader star diagonals can be combined with the Universal Filter Changer; for a T-2 star diagonal you need parts #2459115, #2459110 and #2459130, and the UFC can then sit in front of or behind the diagonal.
Should I choose a mirror or a prism diagonal?
There is no general recommendation, but light passing through a prism is refracted, which behind a fast telescope can lead to colour aberrations; for fast telescopes designed for use without a prism a mirror is the better choice, with the limit somewhere around f/6 to f/7. Refraction in a prism also produces less stray light than reflection on a mirror, which is why many planetary observers prefer a prism, and a prism must adapt to the ambient temperature like the rest of the optics.
Will I be able to reach focus with a binoviewer using the Baader T-2 BBHS Diagonal?
The diagonal has an optical length of 43 mm. Compact T-2 diagonals suit binoviewers because their short optical length often still allows focus when other diagonals fail; whether a given setup reaches focus depends on the telescope's backfocus.
How do I clean the mirror surface of the Baader T-2 BBHS Diagonal?
The BBHS silver layer is ageing-stabilised by a protective hard dielectric coating. Clean it only when necessary, with care appropriate to a front-surface mirror.
What is the benefit of the T-2 threaded connection on the Baader T-2 BBHS Diagonal?
They let you choose the nosepiece and eyepiece holder from Baader's T-2 system and keep the diagonal very compact and adaptable to every telescope system.
Does the Baader T-2 BBHS Diagonal come with a nosepiece or eyepiece holder?
No. The product is the core diagonal body only, with male and female T-2 threads. The telescope-side nosepiece and eyepiece-side holder are separate parts of Baader's T-2 system.
What does "Erect image, Mirror inverted" mean for the view through the Baader T-2 BBHS Diagonal?
This is the standard orientation for any 90° astronomical mirror diagonal. The image will be right-side-up (erect), but reversed left-to-right (mirror inverted). For an image that is both upright and correct left-to-right, Baader offers its Amici prisms.
Can I integrate filters with the Baader T-2 BBHS Diagonal?
Yes. You have two main options. First, Baader's T-2 nosepieces carry a filter thread (1.25" or 2"). Second, the Baader UFC (Universal Filter Changer) can be placed in front of or behind the diagonal with parts #2459115, #2459110 and #2459130.
