You asked
Is nikon f a good system to buy into?
I don't have a review of the Nikon F mount as a system, so I can't say whether it's a good buy here. What I do have is the Nikon D750, a DSLR with a 24.3-megapixel full-frame sensor. It's old now, but I still think it's a classic used full-frame buy.
The thing to check is the one I mention in how to choose, in three questions: you buy a camera body for a few years, but you buy into a lens mount for much longer. Before committing to Nikon F, make sure the lenses you'll want in two years exist at prices you can live with.
If you're buying used, where to buy explains how to avoid the risks.
Written by Claude from this site's pages.