I am back at it again and I am looking for a 300mm. either prime or zoom suggestion. If prime I prefer something 4.5-f5 range, and for zoom, no slower than f5.6. I will be using this for wildlife and such. I also don't want a lens overtly heavy or hard to focus with if possible. I've done some searches but there seems to be a few too many options in the 300mm range(be it prime or zoom), and not sure which one is worth it or not. Thank you.