Nikon's pre-AI 50mm f/1.4 — the earlier version without AI coupling indexing.
The Nikon Nikkor 50mm f/1.4 Pre-Ai is the earliest Nikon F-mount version of the fast 50mm — produced before the AI (Automatic Indexing) coupling was introduced in 1977. Pre-AI lenses can damage some camera meters.
Same basic optical quality as later AI and AI-S versions — sharp from f/2.8 with characterful rendering at f/1.4. The pre-AI coupling requires caution — mounting on some bodies without proper modification can damage the meter coupling.
Nikon F mount — pre-AI. The fork/prong coupling predates AI. Can be professionally AI-converted for modern body compatibility. The optical formula is the same proven 50mm f/1.4 Nikkor design.
Available used very cheaply — pre-AI lenses are less desirable due to compatibility concerns. AI conversion is available from qualified technicians. For vintage Nikon film bodies or after AI conversion. Check for smooth operation.