Apertia · Library
What should you record for each planned focus-stack frame?
Log a two-shot 50 mm stack for 1000–1500 mm planned at f/11: record each shot's focus distance, near and far limit, and the setting you actually used.
What the plan gives you to log
When a stack is needed, Apertia's plan lists each shot as Shot 1, Shot 2 and so on, with its focus distance followed by the near and far limits in brackets. Each shot's near limit is the previous shot's far limit, found by bisection so that the frames meet exactly in the model. Plans are kept in the plan notebook on the iPhone, and you can attach a shoot day to a saved plan to get a local reminder that morning.
The notebook keeps the plan, not what happened in the field. A log written while shooting adds the settings actually used, which can differ because the lens's focus ring, the app's display rounding or the subject did not cooperate.
Keep a log row per shot
- Copy the shot number, planned focus distance and planned near and far limits from the plan.
- After each exposure, write the image file name and the focus distance you actually set.
- Note the aperture and any change in camera position or light between shots.
- Mark any shot where the subject moved.
- Keep the original files in capture order for checking the merge.
Worked example: a 1000–1500 mm product shot
On full frame with 50 mm, covering 1000 to 1500 mm in one frame would need f/15.877, rounded to f/16, which is past the f/11.18 single-frame limit. The plan therefore stacks at f/11 and needs two shots. In the app's metric display these appear as 1.13 m and 1.53 m.
| Shot | Planned focus (mm) | Near (mm) | Far (mm) |
|---|---|---|---|
| 1 | 1128.3 | 1000 | 1296.8 |
| 2 | 1531.9 | 1296.8 | 1876.3 |
If you shot the same range at f/8 instead, the stack still needs two frames, focused at 1089.8 and 1334 mm with a shared boundary at 1198.4 mm. A log that says only “two shots” cannot tell these two plans apart.
Common mistakes
- Overwriting the planned distance with the actual one, so a later gap cannot be traced.
- Logging the focus ring's engraved marks as exact distances.
- Skipping the aperture column because it was “the same as planned”.
What a log proves
A complete log makes a stack reviewable; it does not confirm that the lens reached each position or that a stacking program will align the frames. The DOFMaster equations linked below describe the near and far limits being recorded.