FOCAL LENGTH TO PINHOLE (mm)

Using the Pinhole Resource constant. Daylight Calculations
[Focal Length and Pinhole measurements are in mm]

FL
PIN
F#
FL
PIN
F#
25
0.182 137
250
0.577 433
50
0.258 194
300
0.632 474
75
0.316 237
400
0.730 548
100
0.365 274
500
0.816 612
125
0.408 306
1000
1.155 866
150
0.447 335
2000
1.633 1225
200
0.516 387
4000
2.309 1732

[Remember that 25 mm is approximately one inch]