Baader Planetarium 14 mm Hyperion Fine Tuning Ring - Black

Focal length fine-tuning for Hyperion eyepieces (all focal lengths) Up to 40% shorter focal length. Spacer rings fit between the negative lens and the 2" lens mount so that the respective eyepiece focal lengths meet your needs. A 13 mm eyepiece can be converted into, for example, a 9 or 11 mm eyepiece without any loss in quality. Baader Planetarium Hyperion Fine Tuning Ring 14mm