Kodak Direct Positive Panchromatic

Direct Positive Panchromatic 5246 is one of the stranger products Kodak ever sold: a 35mm black and white film that gave you a slide directly from the camera, no negative in the loop. You shot it, sent it through reversal chemistry, and got a positive transparency ready to project. The whole second half of the conventional workflow vanished.

The emulsion was rated ASA 80 in daylight, 64 under tungsten. Grain was very fine, which made sense for a product intended to be projected at twenty times enlargement. The reversal path Kodak documented in publication J-3 ran a first development in D-67 for eight minutes at 20 degrees, then a clearing bath, a re-exposure, and a second development. You could do the whole sequence on stainless steel reels in a small tank.

It was always niche. Color slides were the consumer mainstream by the time Direct Positive Pan hit its stride in the seventies, and serious black and white workers preferred negative film for the printing latitude. Kodak's catalog aimed 5246 at scientific, technical, and educational users who wanted projectable black and white without the cost of internegative prints. The product faded out in the early 1980s as projection slides themselves lost ground.

In current production it has no close peer. Adox Scala 50 is the modern stand-in for a black and white reversal slide, but the speed and contrast curve are not equivalent. CineStill BwXX reversed in a kit approximates the look, though contrast is harder and grain coarser. If you find genuine 5246 in a freezer it may still produce something, but the base often shows fog, and reversal sometimes amplifies that band into streaks across the highlights.

Reciprocity exponent is 1.31. Zone Light Meter applies the correction past one second on the standard curve. A metered reading of 75 seconds becomes about 90 seconds at the negative, with the correction growing wider as exposures lengthen. For tabletop scientific work at small apertures, where 5246 saw most of its use, the correction came up routinely.