Gift box
Focal length = 92mm
Optimum pinhole size = 0.43 = #10
f/ = 214
iPhone box
Focal length = 45mm
Optimum pinhole size = 0.298 = #13
f/ = 214
Ilford 5x7 box
Focal length = 75mm
Optimum pinhole size = 0.38 = #12
f/ = 197
Tin can
Focal length = 105mm
Optimum pinhole size = 0.45 = #10
f/ = 233
Fluevog shoe box (A)
Focal length = 120mm
Optimum pinhole size = 0.495mm = #9
f/ = 243
Pinhole measurements as per calculation (no rounding) with needle size to the nearest value of pinhole measurement.
Pinhole size and f/ formulas (Tatnall 2017)
Sewing needle diameter = Sewing needle number
0.25 = 15
0.30 = 13
0.36 = 12
0.45 = 10
0.53 = 9
0.61 = 8
0.69 = 7
0.76 = 6
0.86 = 5
0.94 = 4
1.02 = 3
1.09 = 2
1.17 = 1
Formula for optimum pinhole size
The square root of the (focal length x 0.00055) x 1.9 = pinhole size .mm (Tatnall 2017)
Formula for aperture size
Focal length ÷ pinhole size = aperture