With the Firmware update 4.0 Focus Bracketing and Focus Stacking are now possible using the E-M1.
Focus Bracketing is the function to take a series of shots at different focus positions. Focus moves successively farther back from the initial focus position.
You can choose the number of shots using [Set number of shots], the change in focus distance using [Set focus differential], and the charging time for the external flash.
However, unlike focus stacking, focus bracketing does not automatically composite images in the camera, so you need to use third-party software to do so.
Focus Stacking is where eight frames are shot at one time by automatically changing the focus point slightly from the initial focus point, and creating a composite image in the camera
that is focused on a broad range from near to far field.
You cannot choose the number of shots (automatically fixed at 8) but you can change in focus distance using [Set focus differential], and the charging time for the external flash.
Focus stacking is only possible when a supported lens is attached.
Chapter 15, Page 173 & 174 in the revised E-M1 Manual contain the instructions. But is limited in details how stacking/bracketing actual works.
A few points to hopefully make things clearer when selecting these functions.
1. You need to go into Shooting Menu 2, Bracketing On and scroll down to Focus Bracketing to access all the settings.
2. When you turn ON Focus Stacking this heading will show up on top of the settings menu. The [Set number of shots] will be greyed out as it is not available for Focus Stacking (the screen shot in the manual is not
correct). You can scroll down to select/change [Set Focus Differential] and/or [Flash Charge Time].
3. You need to turn OFF Focus Stacking to select/change the [Set Number of shots] function. Then you are using Focus Bracketing and this heading will show up on top of the settings menu.
4. Set Focus Differential ranges from a narrow setting of 1 to a wide setting of 10. The narrower the settings the closer the focus points are together. The wider the settings the wider the focus points are apart.
5. When using Focus Stacking, the focus point initially moves forward at Frame 2 from the initial focus point. Then moves back slightly forward of the initial focus point at Frame 3, see images below. You need to factor this in when framing/selecting the initial focus point.
I have been doing some more experimenting with focus stacking, particularly which is the best focus differential point and where to set initial focus.
Nothing very scientific or a real close up/macro , but just to see how it works.
Mounted my E-M1 and 40-150mm on a tripod at about 45 degree downward angle.
Subject is a tape measure on a table. Note tape measure is not completely flat on table as it bends between the edges. Set initial focus point on the numeral 10 at a focal length of 150mm.
I then shot test images from focus differential point 1 (narrow) through to 10 (wide) at different apertures.
I found that focus differential points 3-5 seemed to give the best overall result with most numbers in focus across the range.
The best result in my test was setting 3 with an aperture of f5.6. This is only using Single Focus point, I have yet to test the other focus settings.
Focus Stack using differential point 3 focused on the no 10.
As the focus differential point goes wider a greater DOF range will be achieved but this will cause some focus points to be out of focus because of the wider focus step (movement) range.
Focus Stack using differential point 10 (wide).
When the images are being taken in focus stacking mode the focus point initially moves forward at Frame 2 from the initial focus point. Then moves back slightly forward of the initial focus point at Frame 3, see images below.
Frame 1, initial focus point.
Frame 2, focus point has moved forward by about 5/8 inch (16mm)
Frame 3, focus point has moved back but still foward of initial focus point.
I created a GIF of the 8 frames but the image is too big to load here. But it clearly shows these sequences.
I also loaded the same individual images (setting 3) into a Stack in PSCS6 and used Auto-Align Layers & Auto-Blend Layers to compare with the in-camera result.
I really couldn’t tell any difference so this in-camera focus stacking is effective with stationary subjects and using a tripod.
Hope you find this useful.