Focus Stacking

Focus stacking means combining a series of photos where each of them has a different focus point on the subject. When they are stacked, the resulting image has all points in focus.

There are several software solutions for achieving focus stacked images. It can be done in Photoshop for example. Other well-known stacking apps include Zerene and Helicon. There are less well-known solutions too including “Focus Stacker” by Boltnev and Kacher, which so far is only available on Apple OS.

Each of these apps starts by aligning the images. This is a critical step, particularly with handheld photo sequences as these inevitably have the subject at different points within the frame because of hand movement. Once the app has aligned all the images, it then goes through them one by one and adds the parts that are in focus to the composite image.

All the apps mentioned above do the job well. However, the alignment stage is critical for handheld insect photos in the field. Currently, the best of the apps in this regard is definitely Focus Stacker, with Zerene performing best in the second stage of assembling the image. Overall, the Focus Stacker app is best for insect photos in the field, with Zerene in second place. For studio/laboratory photos, the alignment stage of the process is less important, because the camera is mounted in a firm position. In those circumstances, Zerene becomes the best choice. However there are multiple solutions on the market and it may be worth exploring those, particularly if you are not using the Apple platform.

The following video illustrates the use of the software in a simple situation of a few shots using the Boltnev and Kacher “Focus Stakes” app. However, it is perfectly possible to focus-stack dozens, or even hundreds, of photos into one image. (In this video, we will also have a quick look at the post processing approach too).

Sometimes you can make mistakes in the stacking process. All is not necessarily lost however and it may be possible to recover the photo in post-processing. Here is one such example. The following output image isn’t good enough, but in post processing we can ameliorate some of the problems.

For this example we used Zerene stacking software. Please note that Zerene did its job very well. The deficiencies were down to human error in taking the photos. It is those errors that we will attempt to fix using Lightroom and Topaz (described in the “Post-processing” tab).

Stacking in blocks

If you stacking a small number of images, as single stacking operation will work fine. However if there are a lot of images to be stacked - say 30 or more - it is often a good idea to stack them in batches of say 10-15 images and then subsequently ‘stack the stacks’ into the final image. The reason for this is that when doing large stacks the software can struggle to do the alignment task properly; with a large number of shops, there may be a lack of a common point of reference that is in focus for all the images.