The Baader Planetarium M43 to M42 step ring adapter is designed to connect DSLR style cameras to Hyperion fixed-focal length and Hyperion Zoom Mark III eyepieces for projection photography.
Simply remove the rubber eyecup, and thread the step ring onto the eyepiece. Then thread the T-ring onto the step ring.
Note: This ring is not compatible with Hyperion Zoom Mark I or II eyepieces. There is a separate adapter for these older eyepieces.