Telecentric systems are mainly used with h-alpha filters for solar observation, in which the etalon in the h-alpha filter, which is plane-parallel to 1/100 lambda, requires a perfectly parallelised beam path over the entire image.
The achromatic telecentric TZ-4S is designed for the entire visible spectrum and can therefore be used for more than just H-alpha systems.
Due to the parallel beam path, it is very good-natured with regard to the working distance: While the magnification factor of a classic barlow lens changes with the distance to the eyepiece or camera, the magnification factor and image quality of the TZ-4S do not change, even if the camera or eyepiece are mounted significantly behind the designer working distance of 97mm from T2.
The achromatic TZ-4S illuminates an image field of 36 mm at a distance of 97 mm from the main body. The contrast is better than with simple barlows or the eyepiece projection often used for high magnifications. With the 4x telecentric, the necessary high visual magnifications can also be achieved together with long focal length orthoscopic eyepieces. The interpupillary distance of the eyepieces used does not change either. The focus position only changes by 3 mm outwards when using the 2" plug-in connection compared to a 2" eyepiece.
The telescope-side connection is made via a dual 1.25"/2" receptacle with safety kerfs (these prevent tilting due to an incorrectly positioned locking groove and at the same time provide a secure hold).
On the camera side, the T2 thread offers a tilt-proof, fixed connection even to heavy cameras or T2 eyepiece clamps.
The TZ-4S telecentric was specially developed for the Baader Solar Filter SunDancer II TZ-3S H-alpha 2"/1.25" and replaces the 3x telecentric built into it. This means that the SunDancer II H-alpha filters can also be used on telescopes with f/7-f/8 with the optimum focal ratio of around f/30.
Please note: The H-alpha blockfilter, which is inserted into the front of the TZ-3S, must be converted into the TZ-4S for this purpose. The blockfilter is not available separately! Please refer to the instructions under "Downloads".
The ideal working distance when using the SunDancer II after the conversion is 70 mm from the threaded base of the T2 connection of the SunDancer II H-alpha filters (instead of 65 mm with the original TZ-3S).
