Originally posted by Raye Is Nikon the camera that you can only by nikon lenses for? Or is it another camera that you HAVE to purchase their lenses?
Camera systems are designed with something called the
flange-focal distance or
register, the distance from the lens mount to the frame (film or sensor). Shorter-register lenses on longer-register cameras can't reach infinity focus. I won't bore you with numbers, but some register relationships (from longer to shorter) are:
Nikon > Pentax > Sony > Canon > Leica > m4/3 > NEX > Q
Nikon, Pentax, and Sony lenses can be adapted to Canon, m4/3, and NEX cameras, but not the other way around, not without IQ-killing optical adapters. Canon cameras can accept all sorts of lenses; that's why Canoneers keep taking our Takumars!
Medium-format lenses have longer registers and can be adapted for Nikon. Otherwise, Nikons can only use Nikon-mount camera lenses for general photography. Shorter-register lenses like Pentax *can* be used on Nikon cameras without optical adapters, but only for macro or other close work. And enlarger (EL) or copy lenses can be mounted on Nikon bellows; ELs longer than 90mm can reach infinity focus on most bellows. But most toggers don't bother with such niceties. Nikon owners generally stay in their rut.
So the answer to your question is: Of current FF and APS and 4/3 camera systems, Nikon is the least adapter-friendly.