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Baader T-2 90° Prism Star Diagonal Body # T2-01C 2456005

Baader T-2 90° Prism Star Diagonal Body # T2-01C 2456005

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Please note that this listing is for the item shown in the first two photos ONLY. The additional items shown in photo 3 are illustrative only and are NOT included.

  • Precision-engineered prism-based star diagonal offers minimal light scatter for high-contrast planetary views at high magnification 
  • Configurable with 1.25” and 2” Baader T-2 nosepieces, 1.25” eyepiece holders, and other accessories (not included with this diagonal body) to suit a wide range of telescopes and applications
  • Full 32mm clear aperture
  • Ideal for compound telescopes and refractors with focal ratios longer than f/7
  • Offers a compact size and short optical path where space is at a premium and short back focus is essential
  • Superb mechanical fit and finish

PLEASE NOTE: This Baader T-2 90-degree prism diagonal with 32mm clear aperture consists of a diagonal body with prism ONLY and includes no nosepiece or eyepiece holder. It has standard T/T-2 threads at the input face (with female T/T-2 thread on the telescope side) and at the output face (with male T thread on the eyepiece side). This lets you add Baader Planetarium T-2 adapters and accessories to configure the diagonal to your needs.

A Fully Customizable Diagonal Body

One of the key features of this Baader T-2 diagonal – and all Baader diagonals, whether they use prisms or mirrors - is the large free aperture and the flexibility to directly adapt to almost any telescope system, without the restriction of a 1.25" barrel size which may cause vignetting in long focal length 1.25" eyepieces or when using the diagonal with a binoviewer. That is precisely why Baader offers the body of all their T-2 System diagonals without adapters.

Baader Planetarium has worked hard to make the finest and most precisely-engineered prism-based star diagonals on the market today. This mid-sized and highly flexible Baader T-2 90° prism diagonal body is ideal for high-power planetary viewing or for systems where back-focus or space is limited and a full aperture 2" diagonal will not work or is not flexible enough.

Highest Contrast and Short Optical Path Length

Like all prism-based star diagonals, the Baader T-2 90-degree prism diagonal has many advantages over mirror-based diagonals. It has a short optical path length. It exhibits minimal light scatter and provides high contrast images. And its reflective properties do not degrade with age.

The optical-grade glass prism in this Baader diagonal is precisely ground to the correct angles for maximum reflectivity and polished to minimize loss and scatter at the air-glass interface. The prism is multi-coated to maximum transmission, then mounted in a precisely machined aluminum housing to ensure the glass remains in the correct location and orientation for maximum performance and long life.

This diagonal works well for observing nearly all celestial objects. But since it minimizes scattered light and wavefront error, it’s especially good for high-contrast and high-magnification planetary and double-star observation with Schmidt-Cassegrain and Maksutov-Cassegrain telescopes and with refracting telescopes of focal ratio longer than f/7. While this diagonal works with telescopes of shorter focal ratio, especially when observing fainter objects, the steeper angles at which light passes through the prism may cause some chromatic aberration when observing planets and other bright objects in faster refractors.

The smaller size of this diagonal is a great advantage with smaller fork-mounted compound telescopes where larger 1.25” and 2” diagonals cannot ‘swing through’ the fork.

Configuration Suggestions

You can configure the T-2 Prism Diagonal to exactly suit your viewing requirements. The input and output T/T-2 threads integrate with the full range of Baader Astro T-2 System components and other T-threaded adapters. The telescope side can be configured to fit 2" or 1.25" focusers, as well as directly onto telescopes with specific threads such as original M44 Zeiss threads, Vixen OTAs, or Russian Maks.

The eyepiece side can be configured with 1.25" eyepiece holders. Or it can be used with Baader's quick change ring #6 to mount the Mark V binoviewer to achieve the shortest possible backfocus distance between telescope and binoviewer. It's also the perfect diagonal for the Baader / Zeiss Giant Binoviewer (it replaces the normal prism diagonal) as well as the Baader Maxbright Binoviewer. With the right accessories, this diagonal also integrates well into digital imaging applications.

The effective optical path length of the base T-2 Prism Diagonal is 35mm. The diagonal weighs just 4.6 oz (130g).

NOTE: Like mirror-based star diagonals, but unlike diagonals with an Amici prism, this diagonal gives images that are upright but left-right reversed.

Manufacturer part number: T2-01C or 2456005.

Note: Occasionally, the product you receive might have a slightly different cosmetic appearance or labeling than what is shown. This can often change from batch to batch according to the whims of the manufacturer. However, you will always receive a brand new, original product as described above.

Description copyright: Agena AstroProducts - Reproduction without permission prohibited.

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Filed under: Eyepieces & Accessories