0.5X Reducer for Photography And Observing - 1.25" Filter Thread (28.5x0.75MM) on Both Sides - Reduces The Focal Length for Visual and Photographic Use

• 85mm focal length, reduction factor of about 0.5X, depending on spacing. 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.
• 2 lenses for better correction - cemented together and coated, black-anodized aluminum housing.
• Mounting threads - 1.25" filter thread (28.5x0.75MM) on both sides: Threads into eyepieces, camera adapters, and other accessories with standard 1.25" threads, and can be stacked with additional 1.25" threaded accessories.
• Free light transmission - 22.5mm lens aperture. Can be used with additional spacers (available separately) to achieve further focal reduction.
• Intended for use with with longer-focal-ratio telescopes and eyepieces of narrow to moderately-wide apparent fields of view.