Released to accompany the launch of the e 3 professional d slr the dust and splash proof olympus ec 20 2x teleconverter lens will double the focal length of olympus 43rds system lensesthe zuiko ed50 200 f28 35 swd lens which covers 100 400mm in 35mm format becomes in effect a 200 800mm lens in 35mm format this converter saves you both time and money a firmware upgrade is available for improved af with the 90 250 f28