I use this technique quite often for my multi-image focus stacked Dragonfly (or other subjects) images. Shooting @ f/5.6 or even f/8 to get smoother looking backgrounds around the dragonfly it is hard to get the wings & tail sharp. So I tend to quickly photograph 3 to 8 images of different focus areas on the dragonfly. Or even more depending on the position of the dragonfly or the size of the subject. In the beginning to get used to doing this technique shoot more focus point areas. You may not need them all, but you have them just in case. These images were shot with a Canon 300mm f/4 lens on a Canon 7d, handheld.
Select images for the focus stack and Load the files into 1 layered Photoshop file-
Load the files into one layered Photoshop file
Select layers & auto align the layers (with all layers selected)
Choose Auto-Blend layers (with all layers selected)
Check box for Stack Images and Seamless Tones & Colors. Try Content Aware Fill Transparent Areas. Sometimes works well, other times does not. You can just crop in on final image which I usually do.
After Auto Blend you can see Photoshop selected the sharpest areas from each layer to blend and put the final blended image on top in the layers palette. You can see the “Masks” Photoshop made for each of the layered images in the PSD file.
My Final Steps are to save the layered file. Then Flatten the layers if you need to do minor touch-ups here or there. Sometimes you will need to do a very slight touch-up or cloning, but nothing major.
These are also similar to doing Multi-Image Panoramas. Or try a combination of Image Stacks & Panoramas in the same file. So you can experiment with different effects. Comes in handy quite often when out in the field photographing. Cuts down on lugging a lot of lenses or even a tripod with you. Try it and let me know how you do! But if you like shooting with a tripod you can use the same steps with a tripod!