I think you'd be happiest with a really GOOD optic....one that has minimal color fringing, is sharp, focuses FAST, balances well when used hand-held, and which is a good fit for high-quality Nikon teleconverters. There's one such lens I can think of--the 300mm f/4 AF-S from Nikon. it works very well with the 1.4x TC1.4e or e-II converters, to make a 420mm f/5.6 with autofocus. On its own, it focuses pretty fast in AF, and it focuses very,very CLOSE for a 300mm lens!!! it can function as a sort-of-macro-lens on close-distance butterflies, snakes, plants,etc, and is good at zoos, on walks, and so on, due to its exceptionally close minimum focus distance. Optics are very good (most would say excellent). Plenty of used ones on the market. $900 to $995 spent on this will give you QUALITY files, which can be cropped-in on. It's sharper than the Sigma 100-300 f/4 EX HSM I own (which i always liked for baseball and softball, and for some outdoor candid shooting). Some of the zooms in this range are f/5.6 or even f/6.3...that is right at the critical edge for lens speed. You really need to keep in mind that this lens is ALSO a pseudo-macro lens with a 12mm extension tube added! And--your $995 is going to be invested in a lens that will not depreciate over the next ten years...not so with a Sigma or Tamron or whatever.