How this calculation works
Use the approximate pupil-ratio-one geometric macro DOF. Place the first modeled focus center half a DOF beyond the near boundary, then add overlapping intervals until the desired object depth is covered.
Approximate DOF = 2 × f-number × CoC × (1 + magnification) / magnification²; step = DOF × (1 − overlap)A worked example
At 1× magnification, f/8 and 0.02 mm CoC, approximate total DOF is 0.64 mm. With 30% overlap, a 0.448 mm step and eleven focus positions cover about 5.12 mm.
Good to know
Geometric object-space approximation, not a camera motor setting or sharpness guarantee. Assumes pupil magnification one; ignores diffraction, motion, breathing and changing magnification. Maximum 10,000 positions.
Reference: Edmund Optics: depth of field and depth of focus (opens in a new tab) ↗
Choose a blur criterion rather than a universal sharpness number
Circle of confusion is an image-plane tolerance that defines acceptable geometric blur for this model. Different output requirements can justify different criteria; the calculator does not select one for a camera.
The approximate macro formula also assumes pupil magnification of one. Lens asymmetry and optical design can change the relevant depth behavior.
A stack interval is not a lens motor increment
The step is expressed in object-space millimetres. A camera’s focus-step menu may use uncalibrated motor increments, so the calculated number cannot be copied into that menu without a separate relationship.
The first interval begins at the near boundary and is centered half a DOF beyond it. Subsequent intervals overlap by the entered fraction instead of treating every frame as a disjoint slab.
Count coverage rather than only dividing total depth
One frame already covers one modeled DOF. Extra frames add one step each, so the count uses the remaining depth after that first interval. A target shallower than a single interval needs one position.
Stopping down can increase geometric DOF while also changing diffraction and image quality. This page does not claim the largest numerical DOF gives the best finished stack.
Use the result with the next measurement
The camera field of view and scene coverage calculator estimates framing under distant-focus rectilinear geometry. It does not supply the macro magnification or focus-step calibration needed for this stack plan.
Geometric object-space approximation, not a camera motor setting or sharpness guarantee. Assumes pupil magnification one; ignores diffraction, motion, breathing and changing magnification. Maximum 10,000 positions.
A few questions, answered
Can I use the step as a camera focus-step number?
No, the result is object-space distance, not a motor increment.
Is diffraction included?
No, the DOF approximation is geometric.
How is the first position chosen?
Half a modeled DOF beyond the near boundary.