rolllog

Tool

Reciprocity calculator

Long exposures need more time than the meter says. This uses each film's own datasheet: a formula when the manufacturer gives one, its table otherwise. Nothing is extrapolated past the published times.

Metered 30 s

51.6 s

  • Same as opening up 0.67 stops

Interpolated between two datasheet rows (highlighted below), on a log time scale. Not a published value.

Kodak T-Max 100: datasheet values

MeteredOpen upOr exposeDevelopment
1/10000 s+0.33 stops——
1/1000 sno change1/1000 snormal
1/100 sno change1/100 snormal
1/10 sno change1/10 snormal
1 s+0.33 stops——
10 s+0.67 stops15 s—
1 min 40 s+1 stop3 min 20 s—

Source: Kodak Alaris F-4016 (2016-02)

Everything else about this film: Kodak T-Max 100.

Same data from the API

curl https://rolllog.io/api/v1/reciprocity