Pinhole Apertures

The values below are calculated by the formula offered by Bob Dome:

         ______
  R  =  V  WCF

where R = radius of aperture
      W = wavelength of light
      C = constant
      F = focal length

The F stop is determined by dividing the focal length by the pinhole diameter. The needle # is the needle that approximates the diameter indicated and can be purchased at many fabric stores.

Millimeters

Focal Length	Pinhole Diameter	F Stop	Needle #
10	.118	84
20	.16	120
30	.20	146
40	.23	163
50	.26	189
60	.29	207
70	.31	224
80	.33	240
90	.35	254	15
100	.37	267
110	.39	281
120	.40	293
130	.42	305	13
140	.44	317
150	.45	328
160	.47	338
170	.48	349
180	.50	359	12
190	.51	369
200	.52	378
210	.54	387
220	.55	397
230	.56	406
240	.57	415
250	.59	423
260	.60	431
270	.61	440
280	.62	448
290	.63	456
300	.64	464	10

Inches

Focal Length	Pinhole Diameter in 1/1000ths	F Stop	Needle #
1	7.4	135
2	10.5	190	15
3	12.8	234	13
4	14.8	270	12
5	16.6	301
6	18.2	330	10
7	19.6	357
8	21.0	381	9
9	22.2	405
10	23.5	426
11	24.6	447	8
12	25.7	467
13	26.7	487	7
14	27.7	505
15	28.7	523
16	29.7	538	6
17	30.6	556
18	31.5	571
19	32.3	588
20	33.2	602
21	34.0	618	5
22	34.8	632
23	35.6	646
24	36.3	661