Originally Posted by
Bill44
Disregard the advice regarding adding a teleconverter to your 70-300 lens if it is a Nikon lens. The Nikon 70-300 lenses will not take a Nikon teleconverter.
The next step up, though not a big one, is the 80-400 VR. Quite expensive and a slow focus due to the screw drive focus. This lens also will not accept a Nikon teleconverter.
Another step up again is the Nikon 200-400, very expensive, fabulous reputation and it will accept Nikon teleconverters.
There are non Nikon alternatives, but some of them have poor reputations, and the ones with reasonable reputations are expensive. The moral of all this is that long glass equals big money.