Macro Photography: What is focus stacking?
In my blog a couple of weeks ago (Creative Photography – Shallow Depth of Field) I looked at understanding depth of field. In particular I was talking about a creative use of a shallow depth of field, where we purposely have only a small part of the image in sharp focus, set against an area of out of focus colour.
Using a shallow depth of field is one of my favourite photographic techniques, but even so, there are some occasions when I want to have front to back sharpness in my photo. Sometimes this can be achieved simply by using a small aperture. But at other times, especially when using macro photography, when depth of field is always a challenge, a small aperture still doesn’t deliver front to back sharpness in your photograph. In this case, you may want to experiment with focus stacking.
f/32 Version Stacking Software Version
Here’s a pair of photos which I took to illustrate this. The top photo was taken at a very small aperture, f32. The photo beneath it was produced using focus stacking software. At first glance, the two pictures don’t look very different.
However, when you zoom into the image, you do start to notice quite a difference in sharpness. Compare the two portions of the bigger picture here – the focus stacked version is considerably sharper than the version at f32, particularly in the further leaf.
f/32 Version Stacking Software Version
So even with my lens set at f32, I couldn’t get front to back sharpness on this flower head – but with focus stacking I could!
Focus stacking is a lot simpler than it sounds! In fact, the software does all the complicated part for you. You will need to have your camera on a tripod, and then you take a series of photos, moving the focusing ring slightly between each exposure.
Start by focusing on the very nearest part of the subject, and continue the series until you have focused on the furthest part. Then the software takes the sharpest part of each exposure and combines them into one image with front-to-back sharpness.
If you have a recent version of Photoshop it will have focus stacking included, or several companies make stand-alone focus stacking software – I use Helicon, and another popular version is Zerene.
It’s best to use a mid-range aperture for this, say around f8, as your lens will perform better at this sort of aperture than it does at f32. Be careful not to joggle your camera as you turn the focusing ring. This technique will only really work with static subjects, so for flowers you need to be either working indoors, or outside on a very still day!
If you would like to learn more about focus stacking and macro photography consider doing Heather Angel's Mastering Macro photography Course
