After my past workshop at Watson Lake, Prescott, Arizona, a participant asked me to explain the Olympus focus stacking process in a macro setting. Since I use the focus bracketing modes almost daily in my macro photos, it made sense. So, follow along to explore capturing focus bracketed images using an Olympus OMD1 Mark II.
First, Olympus offers two different focus bracketing modes – focus stacking and focus bracketing. Focus stacking is a capture of eight images at different focus depths stacked into one JPG within the camera. The original RAW images write to the memory card as well as the finished JPG stack. Focus Bracketing is a capture of up to 999 images at different focus depths and all RAW images write to the memory card for the photographer to stack using other stacking software (Helicon, PhotoShop, etc). This article discusses focus bracketing mode specifically. However, the focus stacking mode is almost identical.
With your camera on a tripod and a lens capable of focus stacking (Olympus 60mm, 12-100mm, etc) frame your shot. I prefer the 60mm and place it as close to the subject as possible. Next, toggle the 1:1 switch on the side of the macro lens and position the camera/tripod to achieve focus. Now, switch to manual focus and focus back and forth to find the part of the image that is closest to the lens. With live view and zooming, manually focus the nearest part of the image.
Now you are ready to activate the focus bracketing function. Using the menu, locate Camera 2> bracketing >on >focus bkt >on. At this point, you are given a choice between focus stacking or focus bracketing. With the focus stacking option set to off, set the number of shots and focus differential for focus bracketing. (With focus stacking ON, these other options are grayed out). In the images below, I demonstrate the difference of a focus stacked image (left) and a single image (right).
Number of shots: I am often asked how to decide the number of images to capture in a stack. That is hard to describe. The more intricate and larger depth of field requires more images. Generally, I start with 50. If there are more than I need meaning some are out of focus because it went beyond my subject, I don’t use those images in post-processing.
Differential: The differential is the distance between each bracketed image and more complicated to calculate. I tend to use a small differential of 1-2 with my macro lens and extension tubes. With more practice you will see different results and learn to adjust according to your subject.
With focus bracketing activated, press the shutter using a cable release. A cable release is crucial to avoid camera movement from pressing the shutter with a finger. The camera captures the images using Silent sequential high-speed shutter and they are viewable on my LCD screen at the same time. If I watch closely, I can see the focus move from the front to the back of the frame. It really is that easy! Now, it is all up to post-processing. My preference is using Helicon Focus, but PhotoShop and other software can stack images as well.
View my camera setup in the video to the left. Notice the camera is upside down on the tripod to achieve the lowest perspective.
If you create more than one stack, you will want to capture a random photo in between each stack. For example, I take a photo of my hand in between each stack. Then when I download, I know where each stack starts and stops.
To learn more about macro photography, check out our book, The Art of Macro Photography. Also available on Amazon.