Hints & Tips

Focus Stacking

George Theodore, December 28, 2018

If one were photographing a landscape from relatively close up to infinity, an aperture setting of f/16 – f/22 would be chosen to render the image sharp front-to-back. The problem here is that with smaller apertures, diffraction causes a degradation in resolution at the far end of our picture. Picture a garden hose closed to its smallest opening; the water becomes a misty spray. Light acts similarly when forced through smaller and smaller holes (apertures).

One solution is to use an aperture such as f/8 (usually the sweet spot of a lens) where the light comes in almost at right angles to our sensor but now we may find we’ve shortened our depth of field. Focus Stacking to the rescue.

This process is similar to shooting HDR but, instead of changing the exposure, we’re going to vary focus. Try this: Manually, on a tripod and in Live View, focus on the closest part of your image, shoot, focus a little further out, shoot and continue changing your focal point and shooting until you reach “infinity”. For landscapes, I’ve found that four to six focal points at f/8 generally does the trick. Several recent camera models have focus stacking “built-in”; i.e. Nikon’s Focus Shift setting in the D850.  Set the start position, enter the number of shots and interval and let ‘er rip. The camera takes the series of images varying focus as it moves through the image front to back (infinity). Neat huh?

But, whether done manually or automatically, we need to stack and blend the images in post processing. Our cameras don’t perform that function internally (yet!). Open the images in Lightroom, choose “Photo/Edit in/Open as Layers in Photoshop”, then in Photoshop,  Select/All Layers, then “Edit/Auto-Blend Layers” (check the box “Stack Images and Seamless Tones and Colors”), click OK, flatten the image and save.

For many years, photographers have used Helicon Focus mostly for macro work. And, since the software basically blends layers, there’s no reason it can’t be used for landscape work as well. The advantage of Helicon Focus is you can save the image in a raw DNG format. Simply specify Raw in – DNG out.