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Reciprocity

Kodak Tri-X long exposures

What a metered time becomes on Tri-X, and the stops it adds — worked out from Kodak’s own data, never past it.

Form T-2

Your metered time

Kodak’s table: 1 s → 2 s, 10 s → 50 s, 100 s → 1200 s, with development reduced 10, 20 and 30 %

The maker’s reciprocity data ↗

Table 1

At a glance

Metered Expose for Added
1 s 1 s —
2 s 5.3 s +1.4 stops
4 s 14 s +1.8 stops
8 s 37 s +2.2 stops
15 s 1 min 28 s +2.5 stops
30 s 3 min 48 s +2.9 stops
1 min 9 min 53 s +3.3 stops

Longer times are beyond the maker’s table and are not published.

Other films with reciprocity data

Other films with reciprocity data

The reciprocity calculator ›