Baader Planetarium 2″/1.25″ reducer with external T2 thread
Looking for a reliable and versatile adapter that opens the door to astrophotography? This reducer from the renowned manufacturer Baader Planetarium is exactly what you need. It combines precise German craftsmanship with a well-thought-out design appreciated by both beginner astronomers and experienced astrophotographers. Its wide range of connection options covers a variety of photographic and visual use cases.
Design and key dimensions
The reducer has an outer diameter of 2″, so it slides effortlessly into any standard focuser or diagonal with a 2″ drawtube. The 1.25″ eyepiece barrel is secured by two locking screws that hold the eyepiece in place via a brass retaining key. This design detail matters - unlike direct metal-to-metal contact, the brass key protects the eyepiece barrel from scratches while ensuring firm, centered retention. The optical length of the reducer is 9 mm, which is an essential value for accurate back-focus calculations when shooting through a telescope.
Thread options and compatibility
The Baader Planetarium 2″/1.25″ reducer stands out for its rich selection of threads on the objective side, making it a truly multi-purpose tool. On the eyepiece side you will find an external T2 thread, complemented by a protective dust cap that shields the thread from dust and damage. On the objective side, the adapter offers three thread options:
- Internal M48 filter thread (standard 2″ filter thread)
- T2 thread for connecting cameras and photographic equipment
- M34 thread
This combination makes it easy to integrate the reducer into a wide variety of optical configurations without the need for additional step-down rings or intermediate adapters.
Typical applications
The most common use is afocal photography, where a camera or camcorder is attached behind the eyepiece. In this setup the reducer acts as a reliable mechanical bridge between a 2″ focuser and a 1.25″ eyepiece, while the external T2 thread allows direct attachment of a camera body via a standard T2 camera adapter. The reducer works equally well for visual observation whenever you need to use a smaller 1.25″ eyepiece in a larger 2″ focuser or diagonal opening.
Technical specifications
| Parameter |
Value |
| Outer diameter |
2″ (fits standard 2″ focuser or diagonal) |
| Eyepiece barrel diameter |
1.25″ |
| Optical length |
9 mm |
| Eyepiece retention |
Two locking screws with brass retaining key |
| External thread (eyepiece side) |
T2 |
| Threads (objective side) |
M48 internal, T2, M34 |
| Dust cap |
Yes - protects T2 thread |
| Manufacturer |
Baader Planetarium (Germany) |
About Baader Planetarium
Baader Planetarium is a German company with a long tradition in astronomical optics and accessories. Their products are designed with an emphasis on manufacturing precision, functionality, and long service life - exactly what astronomers demand. The threads are precision-machined, the surface finishes are durable, and every detail is carefully considered with real-world use under the night sky in mind. If you are looking for an adapter you can rely on even during your most important observation session, Baader Planetarium is a choice that pays off.
