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The more modern Cameras of the OM-D body line of Olympus have some auto stacking feature.

Not to be mistaken withthe focus bracketing. With the bracketing you can create up to 99 images with each of them some slightly different focal pane. This is to stack them in a PC.

With focus stacking the stacking is done already within the camera body. That works surprisingly well even handheld. This example was taken on a stady tripod. Stack mit Fokus Stacker (Stacked with the Focus Stacker App on a Mac.)

In the macro field the depth of field is horribly short due to the large image scale. The only thing you can do is close the aperture, but ...

  1. Doing so results in diffraction. Some think that was horrbile. That is certainly not the case but it is clearly noticiable. See my article about diffraction.
  2. Often f/22 or /32 or whatever the maximum aperture of your lens is, does not provide enough depth of field. A portriat might be sharp from the tip of the nose to the horizon but a macro certainly not.

Focus stacking begins with several photos, bracked in a way that the focal pane is slightly different on each of them. This resuls in a number of images where the most part is blurry but every (important) part of the image is perfectly sharp in at least one of the bracket series. (I think there is a stacking function in photoshop but from what I read not many people actually recommend that.

As I said before, some cameras can do that in-body already. This is what I am about to demonstrate here.

When you stack them manually then you start with scaling each of them in a way that all parts of the image are of the same size. This is because focussing is always a bit like zooming.

Then you compose them in gimp, photoshop, etc. in a way that you use only the perfectly sharp parts of each image.

That is a lot of work. And that is why there is software specialized for this task.

The tricky part of that task is to set the step width of the focus between two individual shots and the aperture in a way the distance of the focus pane of two neighboured images match the depth of field well. 

See this pictures. The aperture was f/6.7, the lens an M.Zuiko 30mm 2.8 macro.  The first one shows an individual shot of the bracketing with the focal pane quite close to the camera. Then we see some stacks, one with step with of 5, 7 and 10. (1 is the smallest and 10 the largest value available) Values smaller than 5 are useful only with quite large image scales, such as typical insect macros. Finally there is one image stacked with the mac software Focus Stacker.

The samples were takein with the OM-D E-M5 mark II and the M.Zuiko 30mm macro lens.

Fokus vorn

Here I focussed on the organge roll of yarn. The auto stacking starts there, then makes zwo image with the focal pane closer to the camera and five more with larger distance, so eight in total.

I set my camera to the option that it does not only save the stacked results but all of the individual steps too. Sounds like wasting memory but allows for stacking them later again in the case that the auto stacking has deficiencies - and that does happen every now and then. 

Fokus hinten

This is the last image with a step with of 5. In this case there is plenty of blurry yarn in the back of the image. That will not look nicely in the stacked image. (see further down)

This is the stacking result with a step with of 5. The part in the front looks quire well but see in the back ...

Das automatisch gestackte Bild bei Schrittweite 7. Das ist eigentlich ganz ok.

This is the step with of 10 where this last one is sharp even to the end.

You'll see further down that this step with may be slightly too large when taken with f/6.7.

Stack mit Fokus Stacker

This is taken with a step width of 7. This step with works best with the auto-stacker already. However, this one was stacked in the post with the Focus Stacker app for Mac.

   

 

Conclusion:

The auto stacking feature comes handy when you want to create macros "on the go" with some larger depth of field than a closed appertrue would allow for. You should store the bracketed photos, too, so that you can repeat the stacking in the post processing. However, when you need really good results, then you should use a tripot and create some way larger bracketing than 8 images and rely on the post processing.