Which lens next?

[Marc-Etienne]

I'm an amateur of wildlife and outdoor photograpy. I own a Nikon D90, a Nikkor 18-200mm VRII, a sigma 105mm macro and a telescope (digiscopy) skywatcher 500mm (with a 3X teleconverter).

I would like advice from other outdoor amateur on which lens should be on my wish list? Right now, I'm versatile (18-200), I can go small (105macro) and can see far (500mm). My question is what would be best next to get a nice basic lenses package for an amateur? Should I go with a wide angle? Should I go with a low light lens? What did you guys do? I would have a budget of not much more than 700-800$

Thanks for advices

 

[tirediron]

My advice? Keep saving. When you get to the $5000.00-ish mark, start looking for a used 400mm f2.8 or 500mm f4. On an APS-C sensor, I'd go for the 400mm just because of the bigger max aperture, which, will allow a lot more flexibility with a TC.