Guide

Focus stacking in Photoshop

Photoshop has stacked focus brackets since CS4, and for a short, well-behaved series it is entirely adequate. These are the exact steps, then the two places it goes wrong, then when a dedicated stacker is worth it.

The steps

  1. File → Scripts → Load Files into Stack… Browse to the frames, tick Attempt to Automatically Align Source Images, and leave Create Smart Object unticked. Every frame becomes a layer.
  2. If you skipped the alignment tick: select all the layers, then Edit → Auto-Align Layers… with Auto projection.
  3. With all layers still selected, Edit → Auto-Blend Layers…, choose Stack Images, tick Seamless Tones and Colors, and optionally Content Aware Fill Transparent Areas to fill the edges the alignment left empty.
  4. Photoshop adds a layer mask to every layer showing where it used each one. Inspect at 100 %. Layer → Merge Visible when you are satisfied, then crop the edges.

From Lightroom, select the frames, right-click, Edit In → Open as Layers in Photoshop, and continue from step 2.

Where it goes wrong

  • Halos at depth edges. Auto-Blend picks whole regions per layer with soft-edged masks. Where a near object overlaps a far one, it often takes the out-of-focus glow from the wrong layer, leaving a bright or dark halo. The fix is manual: paint on the masks.
  • Long stacks. Forty full-resolution layers is forty full-resolution layers; Photoshop keeps them all in memory, and on a laptop the blend can take many minutes or fail. Twenty frames is a comfortable ceiling.
  • Exposure drift. Seamless Tones and Colors hides small differences; larger ones survive as patches.

When a dedicated stacker does better

Helicon Focus and Zerene Stacker are built for long macro brackets: they handle a hundred frames, offer two or three merge algorithms and, above all, a retouching brush for the halos. They cost money and install on a desktop.

The stacker on this site sits between the two: it is free, runs in the browser on any computer, aligns for focus breathing and merges by the same pyramid method enfuse and PMax use, and its memory does not grow with the frame count. What it does not have yet is the retouching brush — so for the occasional difficult stack, keep Photoshop's masks in reserve.