Mushrooms grow remarkably quickly and decay even quicker. But if you time it right they can be quite photogenic. Many species are so small that a macro lens is an absolute necessity. Anyone who has worked with a macro lens recognizes that it can be a real challenge to achieve a sharp subject from front to back and still maintain a nice, soft, defocused background. In fact, with most subjects it's an impossible task. Enter focus stacking or focus bracketing.
The following Olympus cameras have built-in focus bracketing and focus stacking.
OMD E-M1 Mark II
OMD E-M1 (firmware version 4.0)
Not every lens is compatible with the focus bracketing/stacking feature. Here is the most recent list of stacking compatible lenses (as of Dec. 2016).
M.Zuiko ED 7-14mm f:2.8 PRO
M.Zuiko ED 12-40 f;2.8 PRO
M.Zuiko ED 40-150 f2.8 PRO
M.Zuiko ED 300mm f:4 IS PRO
M.Zuiko ED 8mm f:1.8 Fisheye PRO
M.Zuiko ED 30mm f:3.5 Macro
M.Zuiko ED 60mm f:2.8 Macro
A tripod is definitely recommended. However, a few of the shots in this post were hand-held and for others I placed the camera on the ground.
The following steps will set up the camera for focus stacking.
- From within the Menu, select the Camera2 options.
- Select Bracketing. You can bracket a variety of settings (Auto Exposure, White Balance, Flash, ISO, Art Filters, and Focus Bracketing). Select Focus BKT.
- Turn Focus Stacking On.
- Select Set Focus Differential. Choose a focus differential from 1 to 10. This determines the difference in focus position between shots.
- Press OK repeatedly to engage the settings. You should see the letters BKT at the top of the LCD indicating that Focus Bracketing is set.
Although I have found the focus stacking feature to yield excellent results, it is not infallible. There are times where the camera cannot process the stacked image and a message pops up stating, "Focus stacking error. Image composite failed." This is usually due to camera or subject movement, however I have also had it occur when the lighting changes rapidly during the sequence.
I have found the built-in focus stacking to be remarkably accurate. So why would you opt for bracketing vs. stacking? Here are a couple of reasons;
- The stacked image is trimmed. Regardless of subject, which lens you use, or whether you use a tripod or not, the final stacked image is trimmed along all four edges. The final image remains the same size (5184 x 3888px for the E-M1 Mark II), which means some interpolation must be going on. This must be taken into account when composing the shot.
- Details vs distance. The fungus below had countless stalactite-like fingers and was about 15 cm from front to back, a fair distance for a macro shot. I attempted to use the stacking feature, which only brackets and stacks 8 photos. After some experimenting with the focus differential settings I had to compromise. I could capture the details of the front fingers but loose the details in the back, or I could capture the entire distance, but have too much interpolation that would blur out some of the fingers. Not willing to compromise I opted to use bracketing instead.
Upon uploading the images I determined that I only needed 12 of those images to clearly capture the fungus from front to back. I then used Photoshop to stack them. This gave me greater control over the process (which I like), and there was no trimming of the final image. That being said, I really do like the convenience of the built-in focus stacking and how easy it is to use.
It was my interest in the sheer number of mushrooms sprouting up in a local bush lot that inspired me to experiment a bit more with focus bracketing and to write this post. However, there are plenty of subjects out there where focus bracketing can be used. The photograph below is one example, but with full disclosure, it was a complete accident. Shortly after photographing a mushroom, I came across two toads on the trail. I bent down quickly, framed the shot, and pressed the shutter release only to realize I still had focus stacking enabled. Here's that shot.