Solomark Multi-Coated 1.25" 0.5x Focal Reducer Telescope Eyepiece Fully multi-coated optics held in a black-anodized aluminum filter cell. Threads into eyepieces, camera adapters, and other accessories with standard 1.25" threads, and can be stacked with additional 1.25" threaded accessories. Can be used with additional spacers (available separately) to achieve further focal reduction. 0.5x focal reducer effectively halves the focal length of a telescope, enabling lower magnification, a wider field of view, and shorter exposure times for astrophotography. Intended for use with with longer-focal-ratio telescopes and eyepieces of narrow to moderately-wide apparent fields of view.