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.
Focal Length In Inches
Pinhole Diameter In 1/1000ths Of An Inch
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
Focal Length In mm
Pinhole Diamater In mm
F Stop
Needle #
10 .118 84
20 .167 120
30 .205 146
40 .236 163
50 .264 189
60 .290 207
70 .313 224
80 .334 240
90 .355 254 15
100 .374 267
110 .392 281
120 .409 293
130 .426 305 13
140 .442 317
150 .458 328
160 .473 338
170 .487 349
180 .501 359 12
190 .515 369
200 .529 378
210 .542 387
220 .554 397
230 .567 406
240 .579 415
250 .591 423
260 .603 431
270 .614 440
280 .625 448
290 .636 456
300 .647 464 10