Baader Maxbright Mirror Diagonal - T-2

T-2 (M42x0.75) Threads on Both Sides

The telescope side has a female T-2 (M42x0.75) inner connection, and the eyepiece side a male T-2 outer connection with an M34 inner connection. Baader's T-2 star diagonals can be combined with the parts of the T-2 system in many ways. The most important adapters on the telescope side are the 1.25" to T-2 nosepiece (#2458105), which fits all 1.25" eyepiece clamps and has a 1.25" (M28.5) filter holder; the 2" to T-2 nosepiece (#2408150), which fits all 2" eyepiece clamps and has a 2" (M48) filter thread; and the 2"i/T-2a reducing ring (#2958244), which changes a 2" SC male thread into a T-2 male thread with just 1.5mm optical length.

On the eyepiece side, options include the ultrashort 1.25"/T-2 clamp (#2458121, 20mm optical length), the 1.25"/T-2 focusing eyepiece holder with 6.5mm focus travel (#2458125), the ClickLock 1.25"/T-2 eyepiece clamp (#2458100), the 2"a/T-2i expansion ring (#2958242), which changes a male T-2 thread to a male 2" SC thread, and the 2" ClickLock T-2 eyepiece clamp (#2956242). On both sides the Standard T-2 Changer System (#2456321) and the TQC/TCR Heavy Duty T-2 Quick Changing System (#2456322) allow compact connection and rotation of heavy accessories such as binoviewers.

Dielectric Mirror: λ/10, 140 Layers, 99% Reflectivity

The mirror is borosilicate with 1/10 lambda surface precision, and its dielectric coating of 140 layers gives 99% reflectance. It is scratch-proof, durable and absolutely flat.

Baader's dielectric coating is optimised for the visual part of the spectrum: like a UV/IR blocking filter, it has its highest reflectivity in the 400-700nm range and does not pass other wavelengths to the eyepiece. It is absolutely scratch-resistant and suited to the everyday life of a public observatory, and the coating technique keeps the flat mirror surface from warping under the stress of the many layers. Baader was the first manufacturer to develop a dielectric coating for amateur mirror diagonals that does not warp the flat surface under the accumulated stress of the coating layers, and the coating resists even harsh conditions, such as a hut or simple dome with frequent moisture, over many years.

34mm Clear Aperture and 43mm Optical Length

Clear aperture is 34mm and optical length 43mm, and the T-2 diagonals are very compact. Compact T-2 diagonals are recommended for binoviewers because of their short optical length, so that it is often still possible to come into focus when other mirror diagonals fail; this applies most strongly to T-2 prisms.

Example Configurations

For visual use in a focuser you add a nosepiece on the telescope side, such as the 1.25" to T-2 nosepiece (#2458105) or the 2" to T-2 nosepiece (#2408150), and a T-2 eyepiece holder on the eyepiece side, such as the ClickLock 1.25"/T-2 clamp (#2458100) or the focusing eyepiece holder (#2458125). On a Schmidt-Cassegrain the 2"i/T-2a reducing ring (#2958244) gives a T-2 connection with 1.5mm optical length.

For a binoviewer with a T-2 thread, the Standard T-2 Changer System (#2456321) or the TQC/TCR Heavy Duty T-2 Quick Changing System (#2456322) allows compact connection and rotation, which suits heavy accessories such as binoviewers.

Other Baader T-2 Diagonals

Baader also offers a T-2 BBHS mirror diagonal (#2456103) and T-2 prism diagonals. 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.