Optoma - 21.50 mm to 28.70 mmf/2 - Short Throw Zoom LensThe Optoma 21. 50 mm to 28. 70 mm f 2 Short Throw Zoom Lens is a purpose built projection accessory designed to unlock new levels of versatility, clarity, and ease in any display space. With a practical 21. 50 mm to 28. 70 mm focal range, this lens covers everything from wide classroom setups to intimate conference room presentations, all while preserving brightness and edge to edge sharpness thanks to its 1. 2x optical zoom. Its fast f 2 aperture