1. Make the test negatives
- Printing time test: expose it covering one more strip at each interval. Your standard printing time is the first strip where the clear film part stops getting darker.
- Step chart: expose it at the standard printing time, process and dry it fully.
- Both on one sheet: the same two negatives on a single sheet of film, sized to print at 100% inside a 0.25 inch margin. Cut along the dashed line and expose each part on its own, as above.
"PDF page" puts a negative on a page the size of the paper, ready to print at 100% from Preview or a browser.
Chart options
2. Read the print
Photograph the dry print flat and evenly lit, with all four bullseyes in the frame. RAW is best. If you have a reflection gray scale (a Kodak Q-13, a ColorChecker's gray row, or a Spyder Checkr Grey Balance Card), put it beside the print and choose it here.
More options
3. Make a negative
Converts to 16-bit gray, applies the curve, inverts and mirrors. Print it exactly the way you printed the chart.
No curves yet. Read a print in step 2, or add a .curve.json you saved before.
Negative options
Registration marks are a ring and cross on each side, in a 5/8 inch margin outside the image. They print black. Use the same marks on every negative for a print, and line each one up with the marks already on the paper.
Refine a curve
A second pass makes a curve more accurate. Print a check chart through the curve, expose and photograph it like the first chart, then read it in step 2 with "Refining" set to that curve.
Print setups
A print setup is a printer with every driver option fixed, so every print goes out exactly the same way. A curve only holds for the setup its chart was printed with.