Ultra compact apochromatic telephoto lens with a fast f2.8 maximum aperture, and incorporates two extraordinary low dispersion glass elements (abbe number 90.3), to reduce chromatic aberration to a minimum. It incorporates internal focusing which enables responsive and fast auto focus speed. Minimizing Flare and Ghost This new lens has a special coating to reduce internal reflection and minimize flare and ghost, which is a common problem with digital cameras and also creates an optimum color balance. Excellent image quality with ELD glass elements This lens uses two ELD glass elements reduce chromatic aberration to a minimum and also ensure sharp, quality images of high contrast. Rear Filter A drop-in 46mm filter holder in the rear part of the lens barrel can be rotated to facilitate the use of filters, including a polarizing filter, in situ. Inner Focusing System It also incorporates inner focusing system, which enables responsive and fast auto focus speed. The overall length of the lens does not change during focusing, ensuring convenient handling and ease of use. Optional APO Tele-Converter EX Simply adding an APO teleconverter (optional extra), means that this lens can be used as a 420mm F4 AF ultra-telephoto lens with a 1.4X EX teleconverter, or a 600mm F5.6 AF ultra-telephoto lens with a 2X teleconverter.