There are a number of ways to approach stacking images. Sooner or later, if you persist in this technique, chances are you will find them all. And there are, no doubt, methods I have never found. Let me mention a few that I find helpful.
SHORT STACK
The “Short Stack” is where I started from, out of sheer laziness. I had no intention of stacking 50 or 100 images, so I just stacked five or six layers, marching from front to back with them. They gave me a result that was better than my single-shot images at that point, but over time and examination, they also left a lot to be desired. Trying to remove the artifacts in the short-stack found me adding more and more layers to fill in the gaps and behold: soon I was creating longer and eventually long stacks of (sometimes) 100-200 layers.
LONG STACKS
With long stacks, pretty much everything got covered and the artifacts indeed dwindled. Yet, at the same time the image became more and more “clinical,” and, unless I was very careful I could end up with a forensic photo rather than an impression of the subject, which is what I was after.
FOCUS PAINTING
Over time I found that all photography, IMO, was impressionistic, with the exception (perhaps) of forensic photography or photomicography, etc. My idea of an impression usually involved at least some bokeh, areas that were not in focus. Areas of the photo in sharp focus complemented what was not in focus.
This led me to lenses that had narrower and narrower depth-of-field. I will put aside my passion for highly corrected lenses, which would be another blog. Anyway, I found myself searching out lenses that were faster and faster, so I could have lots of bokeh. The fact that these very fast lenses also had narrower and finally laser-sharp field-depth does not bother a focus stacker, because, obviously, we stack focus.
So, I used fast lenses with very narrow depth of field to literally paint focus where I wanted it. And this often included having two or more areas of the image that were in focus and, well, eye-catching.
One of the big differences in focus stacking from traditional one-shot photography is that, unlike a single image where we have one plane and one point of extreme focus, in stacked material the eye is free to wander around the photograph and find an point of focus or, if I offer several, to move from one to another focus point. This fact is what perhaps makes stacked images sometimes have a strange, almost 3D quality, the fact that the eye is not necessarily being limited in direction.
So, focus painting (painting with focus) became a passion and the results were (to me) satisfying. They went a long way to achieving the mental impression that I had of what photography was supposed to do, at least to make me happy.
SMART STACKS
As I explored more and more different kinds of lenses, I found that many were not particularly good for painting focus or were generally too sharp, meaning that their widest f/Stop was too narrow. What to do with these, otherwise, superior lenses?
I came up with the idea of making smart stacks. These are short stacks that, instead of marching from front-to-back like I did with short stacks, I selectively would pick particular parts of the image that I would like to emphasize and take very sharp images of just those points, which then are combined to create a finished image where those particular points are guaranteed to be present.
“Smart Stacks” are also good when there is little time, variable light, or where conditions of wind exist. I do smart stacks more and more lately and generally like the results.
OLD STACKS
And finally, some thoughts about what to do with your legacy stacks. I don’t through away my stacks of images, of which I have over half a million (or more, because I stopped counting), but I keep them and am thankful storage prices keep going down.
One reason I hold on to my stacks is that advances in stacking software and in post-processing software, not to mention advances in my ability to process and retouch stacks (the largest factor) make it possible re-process stacks of images and get great (or better) results.
And there is one other thing I like to do with legacy stacks, when I find the time. And that is, using the smart stack approach I can take an old rather clinical long stack and cherry-pick several images to construct a smart stack that reflects my current way of thinking.
This is especially good when I want to insert more bokeh-like blur into an image, from a large stack that otherwise would be too “sharp,” too clinical.
I include here two images, for fun, comparing the Long Stack to the Smart Stack. No one is better than the other, just different. I use them both all the time. And this may be too finicky for some reads, for which I apologize. This blog really is for dedicated focus-stacking heads like me.
P.S. If you don't see any difference between these two approaches, that is fine. The difference is just a bit of softness.Or, these images show that a 30-layer stack can be approximated with five "smart" layers.
