Coona Skies


Depth of Focus

The following table displays a systems depth of focus in microns for different f-ratios at various frequencies of light. The depth of focus is the amount of focus travel about a point of perfect focus where an image will still be in focus.

The formula used is (depth of focus) = 4.88 * (wavelength of light) * (f-ratio of optical system) * (f-ratio of optical system).

Depth of focus in microns for different f/ratio optical systems at different wavelengths of light.

f/ratio 300 nm 400 nm 500 nm 550 nm 600 nm 650 nm 700 nm 800 nm 900 nm 1000 nm
1 1.5 1.95 2.4 2.7 2.9 3.2 3.4 3.9 4.4 4.9
2 5.9 7.8 9.8 11 12 13 14 16 18 20
3 13 18 22 24 26 29 31 35 40 44
4 23 31 39 43 47 51 55 62 70 78
5 37 49 61 67 73 79 85 98 110 122
6 53 70 88 97 105 114 123 141 158 176
7 72 96 120 132 143 155 167 191 215 239
8 94 125 156 172 187 203 219 250 281 312
9 119 158 198 217 237 257 277 316 356 395
10 146 195 244 268 293 317 342 390 439 488
11 177 236 295 325 354 384 413 472 531 590
12 211 281 351 386 422 457 492 562 632 703
13 247 330 412 454 495 536 577 660 742 825
14 287 383 478 526 574 622 670 765 861 956
15 329 439 549 604 659 714 769 878 988 1098
16 375 500 625 687 750 812 874 999 1124 1249
17 423 564 705 776 846 917 987 1128 1269 1410
18 474 632 791 870 949 1028 1107 1265 1423 1581
19 529 705 881 969 1057 1145 1233 1409 1586 1762
20 586 781 976 1074 1171 1269 1366 1562 1757 1952
21 646 861 1076 1184 1291 1399 1506 1722 1937 2152
22 709 945 1181 1299 1417 1535 1653 1890 2126 2362
23 775 1033 1291 1420 1549 1678 1807 2065 2323 2582
24 843 1124 1405 1546 1687 1827 1968 2249 2530 2819
25 915 1220 1525 1677 1830 1982 2135 2440 2745 3050