small <rant>, was using Edge, the new browser in Win 10 and everytime I'd go to youtube to grab the link to insert here, it would blow away my post. First time I thought it was a glitch, second time I was just dumb and did it again. So now back on Chrome < \end rant>
So let's do this! Focus stacking...what is it? In a nutshell, which most things are, is this: Taking multiple images of a scene at different focus areas using manual focus and using Photoshop to blend them together to one final image. How to do this? Great question.
The setup is easy. Put the camera on a tripod and focus on the closest item in the shot, your subject. Then just adjust the focus a little farther out on each shot, turning the focus ring and taking shots until you get to the end of the focus limiter. (infinity mark)
Can you take as many shots as you want? Of course. Can you use any f stop? sure, for this I used f/1.8. Shutter speed and ISO are irrelevant but if you need a starting point I was at ISO 50 on the sony a7rii and 55 1.8 Zeiss lens using the Joby Gorilla Pod as my tripod. It's great for getting those close to the ground shots. The mode on my camera was aperture priority so shutter speed varied a little.
I took 7 shots to compose this focus stack, and the tutorial is in the video below. The final image is posted just below the video to see exactly how this turns out. Also a gallery of the original images for reference is embedded as well.