Focus Stacking Calculator

Calculate the number of shots needed to achieve front-to-back sharpness in macro and close-up photography.

Focal length (mm)

Aperture (f-number)

Sensor size

Magnification ratio

Custom magnification

Subject depth (mm) How deep is the subject from front to back?

Frame overlap

Shots needed —

DoF per shot —

Focus step size —

Effective DoF range —

Assumptions

DoF at macro distances uses the formula: DoF ≈ 2 × N × CoC × (M+1) / M². Overlap ensures seamless blending in stacking software. More overlap = safer blending.

Focus Stacking Tips

Use a tripod — Essential for alignment. Even small movements ruin stacks.
Use manual focus — Move focus ring or use a focus rail for precise control.
Shoot more than calculated — Better to have extra shots than miss the edges.
f/8–f/11 is usually optimal — Balances DoF per shot vs. diffraction.
Consistent lighting — Use manual exposure and controlled lighting.

Worked Example

Scenario: Macro flower photography at 1:1 magnification

Setup: 100mm lens, f/8, full frame sensor, 15mm subject depth

Calculation: DoF per shot ≈ 2 × 8 × 0.03 × 2 / 1² = 0.96mm

Result: With 50% overlap, need ~32 shots (step size: 0.48mm)

FAQ

What software do I need?

Photoshop (Auto-Blend Layers), Helicon Focus, Zerene Stacker, or the free CombineZP all work well.

Why not just use f/22?

At macro distances, diffraction significantly reduces sharpness at small apertures. Focus stacking at f/8 gives sharper results than a single shot at f/22.

How do I measure subject depth?

Estimate or measure the distance from the closest point to the farthest point you want in focus.

What is magnification?

The ratio of subject size on the sensor to real-life size. 1:1 means life-size; 2:1 means twice life-size on the sensor.

Why does magnification matter so much?

Higher magnifications dramatically reduce depth of field per shot, requiring many more images to cover the same subject depth.