Why the ring is the wrong control
- The focus ring covers infinity down to the close limit in a fraction of a turn, so at close distances a few millimetres of subject distance is a sliver of ring travel.
- You sway further than that simply breathing, and there is a delay between pressing the shutter and the exposure, so the position at the moment of focusing is not the position at the moment of capture.
- The advice repeated by several people was to set focus manually and then move the camera in or out until the subject snaps in.
- Closer is not better. Below the lens's minimum focus distance nothing will focus at all, and the closer you are the more a small lean forward costs.
Why the magnified preview does not rescue it
The camera feature that zooms in while you fine-tune was described as close to unusable handheld — not because the focus drifts but because the framing does. By the time the shot is taken the composition has shifted. The same people said it works well on a tripod, which is the difference: the feature is fine, the hands are the problem.
Depth of field is the underlying issue
- Wide open is rarely right for macro. Even with focus exactly where you wanted it, only a thin slice of the subject is sharp.
- Two ways to widen that slice were given: stop the aperture down, possibly a long way, or back off from the subject and crop afterwards.
- Diffraction at small apertures is real, but the thread judged it a worthwhile trade — slightly less peak sharpness across a usefully larger zone of focus. One reply noted lenses behave differently at close focus and recommended testing your own.
Two things that help before technique does
- Use a tripod whenever the subject allows it. It solves the movement problem rather than working around it.
- Do not compose on the rear screen handheld. Holding the camera away from your body takes your elbows off your ribs, and the weight becomes much harder to keep still.
- For a subject that stays put, focus stacking was raised as the proper answer to shallow depth of field, taking several frames at different focus points and combining them afterwards.