You asked
Is the nikon z 800mm f 6 3 vr s worth buying used?
Yes, I think it's a good one to buy used. Good lenses hold their value far better than bodies, so you pay less to own it and lose less if you sell it later. That's the main argument in Buying used.
It's also a practical long lens. The Phase Fresnel element keeps the 800mm light enough to hand-hold, it has stabilisation and autofocus, and on a Nikon Z APS-C body it frames like 1200mm. It suits wildlife and sport well.
It fits most Nikon Z full-frame bodies, plus the Z50, Z fc, Z30 and Z50 II on APS-C. Check the lens page for the full fit list before you buy.
Written by Claude from this site's pages.