I wanted this lens, but it's a bit heavy for this old guy with a bad back. I just received a Sigma 100-400mm. half the weight and size and on my dx camera it's a 150-600mm.
a few years ago I did the same at my grandson's football games. the parents were thrilled to get action shots of their kids. the problem was with all the printing, I was going broke. glad he got older and quit football.
I was ready to get the Sigma 100-400, but now Tamron has their 100-400. looks like faster auto focusing, and an optional tri-pod collar. I have a Tamron 16-300 and love it. the 18-400 should serve you well.
I would love the D500 but being retired it's a bit expensive for now. I sold my D300 which is an awesome camera for a D7200. couldn't be happier and I can get two for the price of a D500.
I don't know any beginners who would start out with a 3000.00 camera. most will start with the lower priced cameras and move up as the gain more experience. if photography as a hobby is not in their future, they still have a way to shoot family, friends, etc. more logical then spending lots of bucks and then deciding it's not for you.
depends on how much weight your willing to carry. a 200-500 or 150-600 would be awesome, but they are big and heavy. with todays cameras you can crop so I would go with the Sigma or Tamron 100-400.
I was looking at the Sigma 100-400. Tamron is coming out with their own 100-400 by nov. it offers a tri-pod mount albeit for extra $. I would love a Sigma or Tamron 150-600 but with my back problems, I'm trying to hold down on the weight. the Tamron with a converter might suit my needs.