The 2.6x glasspath-corrector is solely designed to provide the necessary backfocus for using binoviewers in conjunction with newtonian telescopes and refractor telescopes. For correcting for the huge amount of glass in our Mark V giant binoviewer (# 2456410) - and likewise in the newly designed Maxbright Mark II binoviewer that is still under preparation at this time.
Both lens elements of the Baader 2x VIP-Barlow (# 2406101) and the 2.6x glasspath-corrector (# 2456317) do look quite similar when inspecting them by eye only (they use the same housing) - and we are very sorry that through the years this is always again creating confusion in the forums. However - we always again reiterate that the two products are not the same lenses and cannot be used for serving a dual purpose.
In case you were ordering the 2.6x glasspath-corrector and would use this product as a 2x barlow lens, you would find out that it creates severe chromatic errors if used in this (wrong) mode. The same accounts if trying to use the 2x VIP-barlow-lens as glasspath-corrector in conjunction with a binoviewer - you would see color error and conclude that the lens were faulty.
We never said that these two products may be used for the other purpose, but always again people look at them and conclude they were the same - which definitely is not the case. Both products work excellent if used for their specific purpose. But since they repeatedly are being (ab)used in either/or configuration, some people concluded both designs were flawed. Again - this definitely is not the case.
Thanks for purchasing the VIP-Barlow if you want a barlow lens. We are sorry but the barlow-element alone is not available. If you intend to use a barlow element only that readily threads into regular 1 1/4" filter threads, we do recommend our Q-Barlow 2.25x Link (# 2956185).
For example, a 1,25x or 1,70 GPC on top of the 1,7x newtonian GPC with a Mark V binoviewer. That would give a nice flexibility.
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.
The cell of this glasspathcorrector must not be opened, because these lenses are seperately centered during manufacturing. Their distances are optimised for use as glasspathcorrector (not as Barlow lens). That's why only "lens position B" is available (cf. the information sheet to the Astro T-2 System®). The 1:2.6 glasspath corrector can be screwed into every T-2 star diagonal, so that you can use it both with Zeiss ringdovetail ot a T-2-thread. So, you can use it with all of our binoviewers.
You can also insert the 2.6x glasspathcorrector – as mentioned above – between every T-2 screw coupling with its flat rim. The flat rim must always face towards the eyepiece and the lens cell towards the telescope.
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.
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!
|Outer Connection (eyepiece/-camera-sided)||Barrel, M34, T-2 (M42 x 0,75)|
|Magnification (x)||1 : 2,60|
|Optical length (mm)||-120|
|Optical Design||Glaspath Corrector|
|compatible telescopes||Refractors, Schmidt-Cassegrain, Newton|