Of course I would like to take a one-shot photo that is perfectly in focus, with enough depth-of-field to fully embrace my subject. I would also like a million dollars, but I have neither. And so I stack focus.
Focus stacking is by its very nature a flawed technique, not in itself, but in its results. By definition, whenever we sample anything, be it audio CDs, DVDs, or layers of photos, we leave something out. That is what sampling entails. All of these methods are lossy by the very nature of sampling. It is simple physics.
So, while I stack focus, the results are, as mentioned, less than perfect. I kind of hold my nose and keep shooting layers, but it is sometimes depressing that the results, while worth looking at, are less than perfect to my eyes.
In the beginning I stacked at narrow apertures, and then for a while I stacked at the optimum aperture for a particular lens, and today I (mostly) stack with fast, highly-corrected, lenses wide open. In other words, I have been around the block with focus stacking.
There are subjects that lend themselves to stacking, like photographing a camera lens or a physical product, and there are subjects that are difficult to stack, like almost anything from nature that has frills, fronds, bristles, and stalks.
And one thing I can say about stacking focus is that it drives home that photography, all photography, is impressionistic, but, with focus stacking this observation cannot be ignored. It is glaringly obvious.
If I didn’t like bokeh, things would be easier, but I do. I like the dreamy, sometimes other-worldly, effect that bokeh offers. Because of that, high-aperture single-frame shooting does not often satisfy me. It is too busy. So, as they say, I am stuck between the devil and the deep-blue sea.
A carefully shot single-frame photo will always have better resolution and acutance than a similar image that is stacked, provided we don’t mind the “busyness” and we put depth-of-field (apparent or otherwise) aside.
Focus stacking is the combining of photos taken at different focus steps. Lately it occurs to me that this includes photos taken at different depth-of-fields, as well. Recently, I have been making stacks at wide apertures and kind of painting on focus with the razor-sharp DOF of fast lenses. And then, after that, I take a reference photo of the same subject at a narrow aperture, say something like f/16.
Let’s say I make a focus stack of a flower. Here I am using Aster flowers. The outer petals are perhaps in greater depth-of-field, thanks to the stack. Then I look at the f/16 image and see that the center of those flowers is in much better definition with the single-shot photo than the stack.
All I have to do is to take the final stacked photo and stack or combine it with the f/16 image and then retouch and copy the center of the flower (with the very sharp f/16 image) onto the stacked image, while leaving everything else the lovely bokeh that it is.
I just thought I would share this approach with those interested.
Nikon D810, CRT-Nikkor, Zerene Stacker
