Theoretic Limits of a Perfect Lens

This page presents a table of the limits of resolution that a perfect lens would return in the ideal situation. Remember, the best consumer grade fine grained film (including professional and all slow speed film) will return between 120 and 140 lines/mm for a typical 6:1 contrast ratio scene. Many film manufactures will quote much higher numbers, but such numbers are for 1000:1 contrast ratio scenes and such contrast ratios can never be fully realized the the real world.

Resolving Power

This presents the theoretic resovling power of an ideal lens where the light's wavelenght is 589.3mu (green).

Tangential lines/mm
f-number Angular distance from axis (in degrees)
0    10    25
1     1391 1329  1035
2     695  665   518
4     348  332   259
5.6   246  235   183
8     174  166   130
11    123  117   92  <--- approx. limits of film resolution
16    87   83    65
22    61   59    46
32    43   41    32
45    31   29    23
64    22   21    16

f-number Angular distance from axis (in degrees)
0    10    25
1     1391 1370  1260
2     695  685   630
4     348  343   315
5.6   246  243   223
8     174  171   158
11    123  121   111  <--- approx. limits of film resolution
16    87   86    79
22    61   61    56
32    43   43    39
45    31   30    28
64    22   21    20

Notes:

• These number hold regarless of camera format or film dimensions
• Emprically, I've seen longer large format lenses that struggle to meet the f/22 resolutions (lenses 300mm and longer)
• One can use these numbers to help determine how good or bad their particular system is when using film to read the lines/mm returned up to the film's ability to resolve (120 to 140 l/mm).