Kepler 0.5x 1.25" Thread Focal Reducer

• Reduces focal length by 2 (and exposure time by 4)
• Multi-coated and anti-reflective optical doublet
• For webcam and visual
• Not suitable for Newton/Dobsonian
• Sink of 31.75 mm

Unlike a Barlow lens, a focal reducer reduces the focal length. The goal is to have a wider field of view and a reduced exposure time in the images (or more signal with an equivalent exposure time). The Kepler 0.5x reducer is a converging doublet placed in a 31.75 mm screw-on aluminum cell. It is only used on small sensors (lunar/solar webcams) or visually.

Caution: Do not use with a medium or large format camera. Due to the Newtonian/Dobsonian's low back focus, the 0.5x Kepler reducer reduces back focus and therefore prevents focusing. Therefore, do not use it on this type of instrument.