Reciprocity
Ilford XP2 Super long exposures
What a metered time becomes on XP2 Super, and the stops it adds — worked out from Ilford’s own data, never past it.
Your metered time
Tc = Tm^P for metered times over 1 s; 1 s or less needs no correction (P = 1.31)
At a glance
| Metered | Expose for | Added |
|---|---|---|
| 1 s | 1 s | — |
| 2 s | 2.5 s | +0.3 stops |
| 4 s | 6.1 s | +0.6 stops |
| 8 s | 15 s | +0.9 stops |
| 15 s | 35 s | +1.2 stops |
| 30 s | 1 min 26 s | +1.5 stops |
| 1 min | 3 min 33 s | +1.8 stops |
| 2 min | 8 min 49 s | +2.1 stops |
| 4 min | 21 min 52 s | +2.5 stops |
| 8 min | 54 min 14 s | +2.8 stops |
| 16 min | 2 h 14 min | +3.1 stops |