Printing calculator
F-stop test strips, dodging and burning, split-grade printing, grade changes, colour-head settings and print-size changes, in one place.
F-stop test strip
| Strip | Total | Expose this step for |
|---|---|---|
| 1 | 4.0s | 4.0s |
| 2 | 5.7s | 1.7s |
| 3 | 8.0s | 2.3s |
| 4 | 11.3s | 3.3s |
| 5 | 16.0s | 4.7s |
| 6 | 22.6s | 6.6s |
Uncover one more strip after each exposure, giving the times in the last column. Equal steps in stops keep the strip evenly spaced in tone.
Dodge and burn in stops
- Burn in: add 2.6s (total 12.6s)
- Dodge: hold back for 2.1s of the 10.0s
Split-grade printing (Ilford method)
Start with 8.0s at grade 0 and 8.0s at grade 5.
- Split-grade printing splits the basic exposure into two (or more): one low-contrast and one high-contrast, giving an infinitely variable contrast range within the limits of grades 0 and 5.
- Ilford’s method uses grade 0 for the soft exposure and grade 5 for the hard exposure.
- Combining exposures is not equivalent to a single mid grade (e.g. 10 s at grade 2½ is not the same as 5 s at 0 + 5 s at 5) because VC paper curves vary across grades.
- Start: test strip at grade 2½; pick the step with some blacks and some highlight detail (go slightly darker if in doubt); halve that time and use it for both the grade 0 and grade 5 exposures on a second test strip.
- The order of exposures has no effect on the final result.
- Grade 0 (soft) exposure controls the light greys/highlights: increase its time for more highlight detail; raise it to 0.5–2 to increase overall contrast.
- Grade 5 (hard) exposure controls blacks and shadows: increase until good blacks; reduce to reveal shadow detail without turning blacks to dark grey.
- More contrast: increase grade 5 time, reduce soft-exposure time, or raise the soft grade.
- Dodging/burning can be done separately during each exposure (e.g. dodge an area during the soft exposure to increase its local contrast).
- Exception: badly underexposed negatives usually need only high contrast.
Source: Split grade printing (Expert Series, Dave Butcher, posted 31 March 2017)
Changing grade (Multigrade filters)
New time: 10.9s(paper speeds ISO P240 for 00–3½, P220 for 4–5)
Newer Multigrade RC papers need far less extra exposure at grades 4–5 than the older “double the time” rule. The papers’ published speeds are used here.
Source: MULTIGRADE RC Papers Technical Information (Oct 2020, 'J20')
Colour head settings for Multigrade
| Grade | Yellow | Magenta |
|---|---|---|
| 00 | 115 | 0 |
| 0 | 100 | 5 |
| ½ | 88 | 7 |
| 1 | 75 | 10 |
| 1½ | 65 | 15 |
| 2 | 52 | 20 |
| 2½ | 42 | 28 |
| 3 | 34 | 45 |
| 3½ | 27 | 60 |
| 4 | 17 | 76 |
| 4½ | 10 | 105 |
| 5 | 0 | 170 |
Ilford: these settings are only a guide because enlargers vary; find the right filtration for your enlarger by testing. Colour heads give slightly lower maximum contrast than Multigrade filters.
Which table is my enlarger?
- Durst-type filtration: Dunco, Durst, Kaiser, Kienzle, Leitz, Lupo
- Kodak-type filtration: Advena, Beseler, Chromega, De Vere, Fujimoto, IFF, Jobo, LPL, Omega, Paterson, Simmard, Vivitar
- Meopta filtration: Meopta
Changing print size
New time: 20.1s(same lens and aperture)
A bigger print needs more time even at the same aperture: exposure scales with (magnification + 1)². This assumes the same lens and aperture and ignores reciprocity, so confirm with a quick test strip at the new size.