Taken tonight with D5200 cheapo 420-800 at 800mm f8.3 and x2 converter, equates to 2400mm i think on crop sensor 1/80s at iso 400. Image not cropped but played about with by my mate 😇 Was very cold and the focusing was difficult so will use LV next attempt.
Look up the spec of the D600 , will suit your needs very cheaply, yes its old but has some fantastic features including FX 24mp, 2xcard slots, 2x user settings, built in flash, built in af drive motor, full hd video the list goes on.
I'm waiting for everyone to go Z then i can get some real bargains, by the end of the year i will probably own nearly every F lens Nikon ever made as the prices drop 😂