Fujinon FS 420mm f/5.6

Fujinon FS 420mm f/5.6 is the field-special long-telephoto LF lens at 420mm — a rare specialty Fujinon variant designed for field use at long focal length with relatively bright aperture.

Key features

• Mount: Copal 3 shutter (1s to 1/125, X-sync at all speeds)
• Focal length: 420mm
• Maximum aperture: f/5.6 (bright for the focal length)
• Image circle: covers 4×5 with movements; covers 5×7 tightly
• Optical formula: Field-optimized telephoto
• Heavy — Copal 3 mount

Use case + rendering

The 420 FS is among the brightest LF long-telephotos — f/5.6 at 420mm is unusual; most LF telephotos at this focal length are f/8 or slower. The bright aperture makes ground-glass focusing comfortable; the trade-off is substantial weight and bulk.

Used examples are scarce; pricing reflects rarity.

Compatible cameras

• Cambo SC / Cambo Calumet 45NX — extended bellows + heavy-duty rail required
• 5×7 + 8×10 view cameras with substantial bellows draw

Related lenses

• Fujinon TS 400mm f/8 — slower 400mm TS alternative
• Fujinon T 400mm f/8 — standard T 400mm alternative