Library · Formulas
Methods at a glance
All shooting formulas answer the same two questions: what the interaxial should be (the amount of depth) and where the convergence should be placed (the position of the depth relative to the screen). The methods differ in the information they use to answer these questions and in the goal they pursue.
Comparison
| Method | Information required | Convergence | Goal | Does not account for |
|---|---|---|---|---|
| Cerit Triangle | main subject distance, lens, aperture, comfort window | main subject (convergence point) | in-focus range limits = comfort window limits | the blurred part outside the in-focus range is not fitted into the window; this is the method's rule |
| 1/30 rule | distance of the nearest object | nearest object | a quick starting value | lens, sensor, screen and the farthest point |
| Bercovitz | nearest and farthest distance, lens, total deviation | nearest object | fitting the depth of the scene into the desired deviation | screen size, position of the main subject |
| Parallax budget | nearest and farthest distance, lens, sensor, budget | calculated | placing the nearest and farthest points on the two limits of the window | shape of the main subject, divergence on a large screen |
| Depth consistency | main subject distance, viewing distance, interocular distance, target roundness | main subject | natural shape of the main subject | fitting the scene into the window |
| Orthostereoscopy | interocular distance, viewing distance; screen and lens for full scale | viewing distance | reproducing the scene at one-to-one scale | other screens, freedom of composition |
Reading the table
- Convergence does not change the amount of depth; it only moves the scene forward or back relative to the screen. It can be readjusted in post-production with horizontal image translation (HIT). See Convergence.
- Interaxial determines the amount of depth and cannot be changed after the shot. See Interaxial.
- The same scene gives a different interaxial and convergence with each method. The calculator's 08 Method comparison table shows the results of all methods side by side for the same inputs.