A beginner's guide to focus stacking
A useful technique often use in landscape, insect and product photography, focus stacking involves ‘stacking’ together images to achieve a larger focal length than that possible in a single image.
When you use a wide aperture (say f/1.4), the focal length is at its minimum, and as a result covers just a small part of an object. This is useful when you want to draw the viewer's eye to just one part of an image, but sometimes you want to show more detail.
You could shoot at a narrower aperture, (say f/16), but moving the aperture farther from a lens’ 'sweet spot' (the sharpest part of the lens) can introduce lens diffraction into the image, resulting in a loss of focus, and may also bring parts of the image into focus that you don't want. At times, choosing a narrower aperture will call for an increase in shutter speed, which may not be possible without increasing ISO and introducing noise.
The solution is focus stacking. This is when you layer photos together at different focus planes to produce one image that is all in focus from the nearest subject to infinity.
In landscape photography you typically only need to focus stack your images when you are too close to a subject and the mid and background is not in focus. Consider those times when you want to have a strong foreground element that leads into another sharp part of the frame - focus stacking can help make this happen. A good example is the sample images here of a tulip field in Wynyard, Tasmania. To do it yourself, you will need a tripod and some time (as focus stacking isn't a quick process).
I shot this image with a wide angle lens (14-24mm). I first got my composition right and then locked down the tripod. I turned on live view and focussed on the nearest point by magnifying x10, then took a photo.
The next step was to repeat the process by shifting the focus point further forward 'into' the frame. You can also adjust for movement, in my case the flower blowing in the wind, by shooting with a faster shutter speed. Take care to layer your images, and move slowly and deliberately through the frame taking images as you go to ensure sharpness. In total I took six images for this image.
Editing
In Photoshop open up all the individual images as layers in Photoshop.
Highlight all the layers and choose edit > auto-align layers.
Crop accordingly and choose edit > auto blend layers (tick seamless tones & colours)
Then, flatten all your layers and voila, you have your focus stacked image.
About the author: Alfonso Calero is a professional photographer based in Sydney, Australia. Over the past 20 years, Alfonso has photographed everyone from politicians to artists and everything from exquisite food to amazing landscapes. See more of his work at alfonso.com.au, book a 1-on-1 photography course with him, or join his workshops in Sydney, Melbourne, Brisbane, Adelaide, Perth, or Fremantle.