I just bought a 5 roll pack of Ultrafine Plus 100 in 120 size, and compared it to some old rolls of J&C Pro 100. The J&C film had a 'firecracker' red inner wrapper and was widely considered to be Shanghai GP3, based mostly on the identical red inner wrapper and same black backing paper.
The Ultrafine film has a metallic silver colored plastic inner wrapper and same black backing paper as the old J&C film. I examined some narrow clips of each film. Both have a slightly purple gray emulsion area. The J&C film has a blue backing that leaves a blue tint in water if I give it a soak. The Ultrafine film doesn't seem to have any backing dye at all, and the back looks like the emulsion side. Soaking it in water doesn't leave any coloration in the water.
Based on this, I'm thinking the Ultrafine film may be Lucky 100. The rest of the description seems to fit. This could be useful if true, because there is a lot more developer info such as times and dilution for the Lucky film than there is for the Ultrafine. The box containing the five rolls has no information on country of manufacture or any expiration date.
I shot one roll at rated box speed in a mid-1930s Voigtlander Bessa with f4.5 Skopar in a Compur shutter that seems to be accurate. The scene was some tree trunks and bushes in direct sunlight, with some shaded areas and a few deeper shadows. The exposure was 1/100 sec at f16. The film was cut into short strips and developed in a homebrew PC-borax mixture at increasing times. My best negs were a little thin, but definitely looked underexposed for this scene. There was no fog. The sunlit objects looked good, the shaded areas had faint density, and the deeper shadows were blank. I shot another roll yesterday of the same scene at EI 25 and will see how that works.
I'm experimenting with an oddball developer, but thinking this film might work best with an EI a bit less than 100 in a 'normal' developer.
