Polaroid Type 55

Type 55 is the film that let you have both. You pulled the print from the Polaroid holder, looked at it, decided you had the exposure right, then peeled the negative away from the pod material and dropped it in a sodium sulfite clearing solution. After a couple of minutes in the bath, you had a 4x5 negative of genuine quality: fine grain, high resolution, usable in an enlarger alongside any conventional sheet film.

Ansel Adams used Type 55 extensively, particularly for documentation work and for situations where he needed to verify exposure in the field before committing a full box of Kodak to a scene. The negative resolution was good enough that prints from Type 55 negatives appeared in his publications. The grain structure was tighter than HP5 or Plus-X in the same format, which made sense given that the emulsion was coating a much more controlled, factory-laminated surface.

ISO 50 is slow for a 4x5 format. At f/22 in open shade you are already below 1/8 second on the shutter, which means a tripod is essentially mandatory. The positive print that came out first was usable for exposure confirmation but had different density characteristics than the negative; experienced Type 55 users learned to read the print as a check and not as a final product.

Polaroid discontinued Type 55 in 2008 when the film division closed. New55, a separate company, produced a compatible positive/negative 4x5 sheet for several years but ceased production around 2018 after a crowdfunding run.

Reciprocity exponent is 1.0. Zone Light Meter applies the calculation past one second. For long-exposure 4x5 work on a view camera, that correction matters; a 2-second meter reading stays at roughly 2 seconds with a 1.0 exponent, while a conventional panchromatic film at the same scene might need 4 or 5 seconds of actual exposure.