Kodak Vision3 250D
Kodak Vision3 250D in Trichroma Lab: 3 frames on 35 mm and 120, developed in Trichroma Lab.
Below them, the film's base as the app measures it, and what the app does with that number.
Frames on Kodak Vision3 250D
Developed in Trichroma Lab and exported as they are — nothing was done to them after the export. Under each: the format, and the camera and lens it went through.
The film base, measured
The bare, unexposed film around each frame — the clear rebate — measured in density on the station Trichroma Lab is calibrated on: under narrowband light at 665, 525 and 455 nm, and under white light through a Fujifilm GFX100S. The light let through is the same reading put the other way round: ten to the minus density.
| Red | Green | Blue | |
|---|---|---|---|
| Narrowband, density | 0.30 D | 0.67 D | 0.94 D |
| Narrowband, light let through | 50 % | 21 % | 11 % |
| White light, density | 0.37 D | 0.63 D | 0.85 D |
Read these as this station's numbers rather than the film's in general: another camera or lamp measures another base for the same film, and two rolls of one stock, developed apart, read apart too — which is why the app grades your roll on its own base wherever it can read it.
What Trichroma Lab does with it
Under three narrow bands, with a flat, it never asks which film you shot: your roll's own base is read off its rebate. This entry comes in when the film is named — under white light, where you always name it, and on a roll whose own base could not be read. It is listed as “Kodak Vision 250D”, and under white light your roll's own base tunes it to your development batch. Narrowband or white light · how trichromatic scanning works.