This is Rokinon"s newest fisheye lens for Pentax. It features some great new features that are not available on Rokinon"s first highly rated 8mm f/3.5 fisheye lens. Optics and glass are high definition (HD) with very clear & sharp images. This lens also features a removable hood which can make it easier for use on full frame cameras. While this lens is designed for APS-C sensors, full frame users can now use it without the hood. On APS-C cameras the pictures will fill the entire frame or screen. On full frame cameras the lens will produce pictures with a semi-circular image and close images will appear proportionately large for a dramatic effect.