Technique

This technique requires you to use a tripod and a remote. I focus on the nearest point of the subject, then work my way back. I suggest:

1. Frame the shot. Frame your shot a little bigger than what you want, as the focus stacking may mean around 5% of the border area is lost. Tip: stacking gives you more data in the final photo, so minor cropping is not an issue.
2. Look at the subject from the side to work out the closet point to the camera lens. Then go to your camera.
3. Make sure the lens is in manual focus mode, not AF.
4. Start live view, focus on the closest point to the lens. Magnify that point to get precise manual focus. Tip: sometimes I move the focus ring back and forward just to ensure the best focus point.
5. Take the first shot.
6. Move the focus ring a smidgen (technical term) counter clockwise. I have seen people say 1mm. I find that is too far. I may move it ½ or 1/3 mm, that is a smidgen. Note: move the focus ring counter clockwise when you are behind the camera where the photographer normally is. Warning: Whether you move the focus ring clockwise or counter-clockwise will depend on the lens and the camera make. While a Canon focus ring is moved counter clockwise, a Pentax 120mm 645 Macro lens is moved clockwise, focusing from front to back. So you may need to experiment to find out the correct direction for your lens.
7. Take your hand off the focus ring, take the second shot, repeat as many times as necessary. Tip: I usually take a couple of extra shots after the furthest focus point. On a camera screen an image looks blurred before it is in real life. Then delete, in post, any images that are really out of focus.

Miscellaneous matters

Other observations:

• At first I found it hard to track focus on the screen at normal size, but before long I began to track it accurately. It just takes a little practice.
• I normally take at least two sets of images, to ensure I’ve got a usable stack. You may need to take more in windy weather.
• I use Helicon Focus and Zerene Stacker to stack images. There are other popular packages. There are different ways to stack that change the final image. A focus stack may fail with one piece of software, but work with another.
• I often extract the JPEG from the raw files and stack those to ensure the stack works. It’s a quick way to test whether the series works, without processing the RAW images.
• Use the most stable tripod you own.
• Several factors influence how many shots you need to take in the sequence including f stop used, focal length of the lens and distance away from the subject. Depth of field (DOF) is reduced the longer the focal length of your lens, the closer you are to the subject and the lower the f-stop number used. Tip: start at f8 and take 3 or 4 photos for a flower 2-4cm across.
• Once you feel confident with the technique, you can narrow your DOF and take more photos. Narrow DOF gives better bokeh.
• I often use a CP filter, to darken colours and take the glare or shine off vegetation.
• Stacking images increases noise in the background of the image. Use noise reduction on the image in post processing.
• Once you understand the basics, it’s time to perfect your technique. I found this ebook very helpful, Focus Stacking in the Wild. Money well spent for newbies to focus stacking. It is all about good technique in the field.

Post Focus

Panasonic now has a feature in its higher end cameras called Post Focus. It has radically changed the way I stack images in the field. It is the only time in my life I bought a camera for one feature only!

The camera is put into Post Focus mode, you compose the shot and the camera does the rest.

It works out the AF points in the image and takes a 6K video (4K in some models) across the AF points in around 2 seconds. You then extract the frames from the video using Helion Focus and stack the image as usual. It has meant a 10 or even 20 fold increase of productivity in the field. My journey learning Post Focus is described here: https://is.gd/Kz3OaY