Hello all! So I have the FD 400mm F4.5 and wanted to get originally the 300mm F4L but then the F2.8 just started getting in my mind because the extra speed will be nice for low light sports and the Bokeh is fantastic. It is a shorter lens than the 400mm so while wider, it would be easier to fit it in my mid size bang instead of carrying the larger one. Of course 300mm is not 400mm but based on the Quality of it, I thought perhaps the 300mm with the Canon x1.4 (highly regarded) will give me the 400mm all in one lens. Of course, if I ever wanted a longer lens like the 400mm with the x1.4 or 2xA adapters, I wouldnt have that option but I dont usually do moon shots or similar so I think I will be fine. Does it make sense to you guys? My plan is to sell the 400mm to help me pay for the 300mm of course.