Technical Pan was a panchromatic black and white film produced by Kodak with unique characteristics that have not been replicated. It was generally used as a very slow film, rated at ASA 25 or even 16, although it could be rated at up to ASA 320. This film had exceptionally fine grain, especially when rated at a low speed, and made excellent enlargements while preserving fine details. Kodak stopped selling it in 2004. It has not been replaced by a film (from any manufacturer) with its exceptional characteristics.

The film could be developed at home, mainly by using the chemical mixture Technidol, which Kodak sold for that purpose alone. To achieve exact results, home development was often the preferred process. Like other panchromatic films, it cannot be developed under a red safe light.

When the film was discontinued, Kodak revealed that none had been made for many years, and that it was still on the market only due to a large roll being found in frozen storage. The film was created for the military and was no longer required for that purpose. Consequently, Kodak cut the roll into commercially viable formats and continued to sell it. Unexposed Technical Pan is now quite valuable and very difficult to find.

Tech Pan, as it is often known, was very popular among some professional photographers and astronomers, as it was capable of recording extremely fine detail, and its sensitivity curve extended much further into the red than that of most films. In particular, it was very senstitive to light emitted by hydrogen at 656.3 nm, which made it very useful for a wide range of astronomical imaging. Tech Pan was also useful for electron and laser photography. The film was popular with photographers in the art and fashion industries for its extremely high-contrast results when up-rated and processed in an abrasive, high-strength developer.

This description comes from Kodak publication No. P-255, copyright 1985:

KODAK Technical Pan Film is a black-and-white panchromatic negative film with extended red sensitivity. The 2415 Film is available in both 35 mm and 4 x 5-inch sizes; it has a dimensionally stable 4-mil (100 µm) ESTHAR-AH Base with a built-in 0.1-density dye that suppresses light piping. The 6415 Film is available in 120 size with a 3.6-mil acetate base. Both 2415 and 6415 Films have good latent-image keeping and a dyed-gel backing to suppress halation and curl.