Today I took possession of the Canon EF 75-300mm f/4-5.6 III ($12 pawn shop find). It will be the "birding" lens for my wife's Olympus. If we'd like to talk about rotten eggs being laid, I think that lens is a good start. Somehow I don't believe the upcoming RF 100-500mm will be in that category by a long shot. On the other hand a photo is what we make it. No amount of money or lens design expertise can fix a rotten photo. A good photographer will do well most times, when he's trying.Canon's, in recent years, has proved they can lay an egg.