Skip to content

Glasspathcorrector 1:1,25 for Baader-Binoviewer with Zeiss ring dovetail (MaxBright® II and Mark V)

SKU GLASS-1Z (Baader #2456314Z)

Note: To enquire or to place an order please press the Add to Quote button and add as many products to the quote as you are interested in. Add any questions or comments in the Message field. We will then get back to you to discuss your requirements. Alternatively, give us a call.

Click for further details on ordering, payment and shipping.

  • Glasspathcorrector Factor 1.25. Optical path length: ≥ -30 mm
  • Insert diameter: ∅ 38 mm
  • Suitable to insert into the Baader MaxBright® II Binoviewer w/Zeiss Microbayonett or Mark V Großfeld (Giant)-Binocular (#2456410)
  • A Baader Glaspathcorrector is not a Barlow lens! The reason for this name (in Germany the name Glaswegkorrektor® is a protected trademark by Baader Planetarium) is only secondly the displacement of the focal point
  • A Glasspathcorrector is primarily intended to correct the prismatic color fringing and slight spherical overcorrection that occurs due to the long glasspath in binocular prisms.
  • Please note: The Baader MaxBright® II Binoviewer with case (#2456460) is the only Baader-Bino where you can choose between Zeiss ring-dovetail and T-2 thread adapter.

Glasspathcorrector (GC) for Baader Binoviewers and more

Glasspathcorrectors for lens telescopes, Newtonians and Schmidt-Cassegrains

A glasspathcorrector fulfills two purposes: On the one hand, it removes the colour aberrations which are caused by the prisms of the binoviewer at fast telescopes, and on the other hand does it move the focus point outwards so that you can reach focus even at telescopes with little backfocus. And you can use different glasspath correctors to achieve additional magnifications without buying a second pair of eyepieces.

Baader Glaswegkorrektor (GK) Faktor 1,25 GC Factor 1,25 / Factor 1,70 / Factor 2,60

These three glasspathcorrectors are inserted either into the binoviewer or the T-2-prism. Which one you need depends on the available backfocus. You can find information on how to determine the backfocus of your telescope in the manuals of our binoviewers. Please also note our special 2" glasspathcorrectors for Newtonians or Lens telescopes and SCs.

The reduction of the optical length was measured with the 2" focuser of a Traveler 105mm/f6 Apochromat with a pair of 35mm ED eyepieces, the Großfeld (Giant) Binoviewer with 90° T-2 prism diagonal and the glasspathcorrectors. The measurement was done with the GC placed between prism and binoviewer. If the GC is placed in front of the prism, the optical length is reduced approximately by another 15 mm.

Optical Length without Corrector with GC 1:1,25 with GC 1:1,70 with GC 1:2,60
From the contact surface of the focuser – with 90° T-2 prism 162 mm (can't reach focus) 144 mm 122 mm 79 mm
straight, with 2" nosepiece (without prism, important for Newtonians) 112 mm 94 mm 71 mm 28 mm
straight, with T-2 quick-changer 123 mm 105 mm 82 mm 39 mm


With these three lens systems, you can solve focus problems of almost all common telescope designs. The lens cell provides both a thread for the Zeiss dovetail of our Großfeld (Giant) Bino and the MaxBright® II as well as a T-2 clamping flange for MaxBright® und MaxBright® II! This flange can be clamped between the male and female threaded parts of every T-2 (M 42x0,75) threaded connection. This way, you can start to experience with many accessories which you couldn't use with your telescope before.

Example for the use of glasspattcorrectors with the Baader Safety Herschel prism.

Example for the use of glasspattcorrectors with the Baader Safety Herschel prism.

Glasspathcorrectors 1:1,25 and 1:1,7

The lens units of these correctors are cemented and can be removed from their cell to mount them upside down. The convex (outwards curved) side must always face towards the telescope. The versions for T-2 and Zeiss dovetail only differ in the mounting direction and can be reconfigured, if necessary.

Zeiss Dovetail (Großfeld- (Giant) Binoviewer and MaxBright II, only for GC 1:1,25 and GC 1:1,7

The glasspathcorrectors 1.25x and 1.7x are screwed into the Zeiss Ringdovetail at the front of the binoviewer.

T-2 Coupling Nut (Maxbright®/Maxbright®II Binoviewer)

All glasspathcorrector are installed with the lens configuration B (lens cell points away from the binoviewer). To do so, there is enough space or a matching thread as well in the T-2 star diagonals as in the 1¼" and 2" nosepieces. To save optical length, the lenses are not inserted into the binoviewer. This way, the beam splitter inside of the binoviewer can be very close to the front of the housing.

Telescopes with T-2 thread

Whenever you can't reach focus with a new accessory for your telescope, because there isn't enough backfocus, you should check if our glasspathcorrectors may be the solution. Almost every telescope manufacturer offers a T-2 adapte for his telescopes. These adapters usually are very short, because they are designed to attach to a DASLR. At exactly this place, our glasspathcorrectors are inserted! We manufacture several eyepiece adapters, spacer rings and adapters with T-2-thread, so that it is almost always possible to create a working adaption.

Camera lenses

Perhaps you still own a camera lens with T-2 thread. With many lenses by third-party manufacturers (e.g. Tokina, Soligor, Vivitar etc.) you can remove the bayonet ring and access a T-2 thread. By using a glasspathcorrector and our Variable Locking/Sliding T-2-focuser or a 1¼"/T-2 eyepiece clamp, you can use your 1¼" prism diagonal and most 1¼" eyepieces together with your camera lens!