This achromatic Baader SunDancer II Telecentric System TZ-3S from Alpine Astronomical is designed for the entire visible spectrum and can therefore not only be used on H-alpha systems, but also replace a Barlow lens. While the magnification factor of a Barlow lens changes with its distance from an eyepiece or camera (zoom eyepieces are also based on this principle), the magnification factor and image quality of the TZ-3 do not change, even if the new focal point deviates very significantly from the working distance of the optical design (65mm).
The achromatic SunDancer II TZ-3S illuminates an image circle of 35mm at a distance of 65mm from the base body, ideal for the small sensors of modern, fast planetary cameras that require high magnification for photographing the moon and planets. The contrast is better than with simple Barlows or the eyepiece projection often used for high magnifications. With the 3x telecentric system, the high magnifications which are necessary for visual observations can also be achieved with long focal length orthoscopic eyepieces. The interpupillary distance of the eyepieces used does not change either.
The connection on the telescope side is made via a dual 1.25"/2" nosepiece with safety kerfs (these prevent tilting due to an incorrectly positioned safety groove and at the same time provide a secure hold). On the camera side, the T-2 thread provides a tilt-proof, fixed connection, even to heavy cameras or to T-2 eyepiece clamps. For the T-2 thread, adapter rings are available for almost all common connection systems (e.g. M48 / 2"/ M68).