52 mm Lens Filter Thread (M52 × 0.75)
Direct Answer
The 52 mm Filter Thread (M52 × 0.75 mm metric pitch) is the legendary standard for 50mm f/1.8 'Nifty Fifty' prime lenses and virtually all vintage manual-focus Nikon NIKKOR AI and AI-S primes from the 1960s through 1990s.
Source: DIN 4503 / Nikon Historical Standards
Specs
| Thread Diameter | 52.0 mm (nominal ø52) |
| Metric Thread Pitch | 0.75 mm (M52 × 0.75) |
| Nikon AI-S Legacy | Nikon standardized 52mm across 24mm f/2.8, 28mm f/2.8, 35mm f/2, 50mm f/1.4, 50mm f/1.8, 105mm f/2.5, 135mm f/3.5 |
| Modern Glass | Canon EF 50mm f/1.8 STM, Nikon Z 28mm f/2.8, Nikon Z 40mm f/2, Fujifilm XF 35mm f/1.4 R, Panasonic 25mm f/1.7 |
The Nikon AI-S 52mm Unification
Nikon's engineering philosophy in the manual SLR era was legendary for maintaining 52 mm filter threads across almost their entire prime lens catalogue (from $20\text{ mm}$ ultra-wides to $135\text{ mm}$ telephotos), allowing photojournalists to carry a single set of yellow, orange, and polarizing filters for black-and-white film work.