根据最新行业消息，佳能或将调整其超远摄变焦镜头的产品策略，放弃此前传闻已久的RF 200-500mm f/4L IS USM开发计划，转而推出更具市场针对性的RF 300-600mm f/5.6L IS ...

What is a mirror lens exactly? And have they got a new lease of life when used on mirrorless cameras? I've been trying them ...