I'm thinking about buying a 300mm lens, at the moment my only long lens is the Panasonic 45-150mm. I have an E-m10 and I think that I will also buy a grip. The question is which lens to buy, to be used for wildlife / birds. No aspirations to become an avid BIF photographer so AF tracking is not a 'must have'. Most logical option is the 75-300 II, if I buy the Olympus I will buy the latest version (€500,-). On the other hand there are lots of Nikon 300mm f4 IF ED available for approx. €400-€500. And another option is a Canon FD 300mm f4L for roughly the same price as the Nikon. These primes must be better lenses and more than a stop faster than the native lens. Any thoughts?