Sakawa Pan is based on Fujifilm 4771, designated "HC Panchro Polyester" — a high-contrast panchromatic motion picture film produced by Fujifilm in Japan. When Fujifilm ceased all motion picture film production on 31 March 2013, the 4771 went with it. No replacement exists.

The 4771 was built for Hollywood's optical-printing chain: travelling mattes (the physical predecessor to digital green screen) and title cards. Our stock came from a film transfer house that used it for titling motion pictures. Kodak's Eastman High Contrast Panchromatic Film 5369 is the documented equivalent — same role, similar characteristics.

Resolving power is estimated at 200–250+ lines/mm, exceeding Kodak Technical Pan (125 lp/mm). Grain is virtually invisible — finer than any modern 100-speed film. The emulsion was engineered for an optical printing chain where every duplication generation compounds resolution loss.

We rate Sakawa Pan at ISO 25. In our testing, the best results came from metering at box speed and opening one additional stop — treat exposure like slide film, not a forgiving negative. Without the extra stop, negatives tend thin. Our confirmed development protocol is HC-110 Dilution B for 6:30 at 20°C (68°F), distilled water, gentle inversions first 30 seconds then 1 inversion per minute.

Developer choice shapes the final image. High-energy developers (D-97, D-19) produce steep, graphic contrast (gamma ~3.6). Compensating developers (HC-110 Dil. B, Pyrocat-HD, Rodinal 1+50) deliver continuous-tone pictorial results with extraordinary sharpness.

The film is coated on polyester (PET) — archivally stable, dimensionally flat, immune to vinegar syndrome. The clear base light-pipes easily; keep the roll in its black cassette until loading, work in subdued light, and take 2–3 blank frames at the start of each roll. The emulsion is soft and scratches easily — handle by the edges, no squeegees. Bulk loaded to 135 by Koltin Sullivan in Los Angeles. Every roll comes from the same coating run (emulsion 738-01, lot 501-08).

Panchromatic sensitivity means total darkness is required for loading and processing — no safelight of any color is safe.