Hand held focus stacking
One of the reasons I first tried and then fully switched to Olympus / OM Systems cameras and lenses was the built in focus stacking and bracketing computational facility. For a lot of my plant portrait, and macro work I need a combination of good depth of field with clean(ish) backgrounds to give both subject separation and sharp focus across as much of the subject as possible. This image of the spring flowering shrub, Stachyurus praecox 'Rubriflora' is a good example:

Although both stacking and bracketing modes work by taking a sequence of images with a progressive adjustment of the focal plane they work slightly differently. Bracketing allows up to 999 images, moving the focal plane through the image from the frontmost point chosen. The images can then be combined into a single image using stacking software (I use Photoshop but others are available). Stacking takes up to 15 images both before and behind the initial focal point and then combines them in camera into a single JPG. When RAW shooting is used the original RAW files are saved with either option but stacking also generates JPGs with the RAW files. Either method works well to generate images with the necessary characteristics of depth of field across the subject and separation from the background but for best results both require a stable tripod to keep the stack of images aligned.
But using a tripod is not always possible. Which brings me to hand-held focus stacking. At 75 my hands and posture are not as steady as once they were. OK, I shake a little. It was only with the more recent purchase of the OM-1 body and it's insanely effective 7 stop IBIS that I've been able to explore hand held focus stacking.
So what works for me? After experimenting I've set up and assigned to a Custom Function the following:
- Focus bracketing - set from Camera settings menu 2 and Computational modes menu - ON
- Number of shots = 5
- Differential = 3
- ISO 250mm - to keep noise low
- Aperture f3.2 - to provide the subject to background separation.
I find this works well to give me both a better depth of field across the subject and, when feasible, subject separation. As with this image of Erythronium tuolumnense, one of the North American trout lilies, taken in a fairly crowded planting.
Or this shot of Snake's Head Fritillaries in a wildflower meadow.
All the images so far were taken were taken with my 40-150 f2.8 PRO lens. This combines superb image quality, extremely fast transitions between the stacked shots, and close focusing, ideal for plant portraits...
...lichens...
... or larger insect shots, albeit with the 1.4x teleconverter attached:
Also working well is my 60mm macro. I don't expect to get the depth of field attainable with tripod mounted shots but anything that produces better results than a single shot with a wide aperture is worth while. Such as this little Heliophilus pendulus hoverfly, photographed in natural light by the side of my little pond. It's not all in focus (abdomen and top wing) but it's given me better depth of field across the eyes and thorax.
What hasn't worked that well is my newly acquired 100-400mm MK II. Yes, the sync IS is great for single hand held shots but the transition speed between stack shots and the weight of the lens conspire to produce too much movement and blur in the final images.
The only niggle I do have is with the Automatic JPG production. This is both a boon and a curse. The boon is that I can immediately see an the in camera stacked shot to see if it has worked and not produced blur or ghosting as images haven't aligned. The curse is that I also generate 6 JPGs per stack, 5 of which are useless for my immediate workflow and a stacked JPG that I also have to delete if I've done a RAW stack.
Of course, hand held focus stacking is subject to the same limitations of any bracketing / stacking operation. Subjects must be still and / or the wind almost zero. But even so it's a valuable technique to provide a good depth of field on the subject with background separation where appropriate.
.