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Baader protective Canon DSLR T-ring with built-in plano-parallel polished Baader 50.4mm, 7nm H-alpha narrowband filter (delivery WITHOUT camera housing)
Baader protective Canon DSLR T-ring
including 2" nosepiece with maximum possible inner diameter, and removable T-2/M48 insert ring.
The protective T-ring for Canon EOS cameras allows maximum free passage of 47.3 mm (M48 thread) any 2" and 50.4mm Baader filter to be mounted in the T-ring to protect the Canon camera body against dust and moisture. So that you can get the maximum benefit from your protective T-ring, there are multiple versions of the protective T-ring available with built-in Baader 50.4 x 3mm filters (see fig. 3). The protective T-ring provides not only imaging free of vignetting with extremely short focal length telescopes, but also offers a very versatile range of connections. The protective T-ring replaces other camera filter systems which must be mounted directly onto the camera body. The glass thickness (3mm) of the installed 50.4x3mm diameter filter is included in the mechanical construction. The resulting effective optical path on any Canon EOS camera is therefore 55mm - exactly the optical path of standard T-rings. If, instead of the normal 3mm thick filter, a normal Baader 2" filter in a low profile filter mount is fitted, the effective optical path differs from the default 55mm by only +0.3mm. This discrepancy is negligible.
