This is one of those topics that get me running in circles. What are my best options, taking a traditional single-shot photo or stacking an image? And if I stack, should it be many or just a few layers. I thought it interesting to go over some of the options. I can’t promise you will get anything of value out of this, but differences may be visible, and the comments at least should make sense.
[Note: I have posted 2048 pixel images of the above at this link as a PDF.
http://spiritgrooves.libsyn.com/photography-shooting-one-layer-or-fewmany-stacked-layersThis is a look at some of the options we have when shooting a single photo, an elaborate stacked photo, a photo stacked with just a few layers, and things like that.
(1) Traditional One-Layer Photo (Sharpest f/stop)
Of course, we can shoot a one-layer photograph. That’s photography’s history, and there is no need going over what that entails. We all live with it. For an f/stop, we can use the f/stop with the overall peak sharpness for that lens, often f/5.6 or thereabouts. Or, we can push the aperture higher until the effect of diffraction stops us. I don’t tend to go this route. No image is shown for this option.
(2) Traditional One-Layer Photo (Highest f/stop)
On the other hand, we can choose only narrow, high apertures, pushing the lens to greater overall DOF, but also increasing diffraction. With very fine lenses like the Zeiss Otus series, we can shoot at something like f/16 and apparently not see (I am sure diffraction is still there) the effects of diffraction all that much. With Adobe Lightroom’s new “Dehaze” feature, some of the effects of diffraction (seemingly) can be removed.
I have been learning to shoot single-shot photos at apertures around f/16 and getting pretty good results, especially with the better lenses. But even at f/16, the results of a single-shot layer does not have the sharpness of a well-done stacked photo. Close, but no cigar. I keep trying this, but so far always go back to stacking.
(3) Stacked Photo, Many Layers
We can stack multiple layers, a great many layers, which puts more and more of the image into focus at the expense of potential artifacts and a kind of “rounding error” in sharpness. Yes, taking 50 or 100 layers puts everything generally more in focus. However, the various factors involved in matching up 100 layers, the ever-so-slight shifts, etc. add up and appear as what we could call “noise” or increased low-level artifacts.
MEDIUM APERTURE
In addition, we can take one of several approaches in multi-layer stacking as far as f/stop is concerned. We can choose the midrange “peak” f/stop for that lens as far as overall sharpness is concerned (and stack away) or we can stack at one of the extremes, wide-open or high aperture.
HIGH APERTURE
Taking the high-aperture route (for stacking) has few advantages, mostly due to increasing diffraction. Stacking is perhaps best done at the peak-sharpness aperture for that lens, although that is not what I prefer.
WIDE APERTURE
I like to shoot wide-open, but this takes a fast lens (if you want bokeh), one that is already very sharp wide-open. Additionally, shooting wide-open means that each layer has a razor-thin DOF, a tiny slice of the overall photo, which means many layers may be required. However, it has the advantage of allowing you to paint focus and have just the bits of the image in focus that you want, and not just in one area of the photo.
We could, for example, have areas of the foreground in focus, the midrange out-of-focus, and then areas of the background in focus. We can select and paint-in focus.
(4) Stacked Photo, Selected Layers
Another alternative is to stack focus at a higher aperture (like f/16), but use very few layers, perhaps picking out the parts of the photo you most want in focus and making each of those a layer. The result is a photo that is sharper and with less noise or artifacts, but also, when looked at carefully, less sharp overall. From a distance it looks quite sharp, but close-up examination shows, of course, only those areas for the particular layers we selected in peak sharpness.
(5) Superimposition of an Image on a Background
I seldom if ever do this, but we should point out that it can be done. Take a photo of a background with pure bokeh and then (using another layer) superimposed a section of the same thing at f/11 or f/16, so that you have the same photo, but featuring one flower or whatever. Here is a crude example I just threw together.
There are no winners here, no free-lunch. Whatever we do enhances one aspect of the photo at the expense of others. Each approach has its merits, but also its disadvantages.
MICROCONTRAST
What worries me most about stacking is the potential loss of what we can call microcontrast. I know, some argue whether microcontrast even exists, but to me, it does. Lenses like the new Zeiss Otus series seem to me to have better microcontrast, which for my work is very desirable.
When we stack photos, especially with many layers (as mentioned earlier), the very fact that by definition a stacked layer involves digital sampling of a larger image means that something is excluded and left out. This, coupled with the minute alterations that occur from changes in lighting (if outdoors) or somehow jarring the camera/tripod, etc. seem to affect the overall microcontrast of the photo. The result is something similar to diffraction. We could just call it, as a joke, “sampling” error. It is unavoidable and usually quite visible, if we look closely. The fact is: most people (as viewers) do not look closely, unless we are purposefully doing so. Photography is about impressions.
However, focus stacking, as mentioned, is a digital impression of an analog image, which is itself an impression. If the impression is satisfying in some way, then I guess it does not matter how many artifacts are embedded in what we are looking at. We get the impression.
DESIRABILITY
We have discussed the disadvantages of stacked photos.
There is also the popular consensus that there is something about a stacked photo image (warts and all) that appears “different” from a single-shot photo. Many people like it. Perhaps it is that messing with the overall (or selective) focus pushes our envelope just a bit, making that photo seems a little bit realer or more vivid than life, almost a touch of a 3D (or psychedelic) look.
And there is also the fact that, unlike a traditional one-shot photo that has a single focus point in the image, with focus-stacking usually there is no single focus point as dictated by the lens, but rather anywhere you want to look is the focus point, so where do you want look first? In other words, there is no focus point embedded in the image that leads or directs your eye, so your eye in some sense is free to look around. There is no doubt that this is liberating, unless you like being led.
Anyway, just some thoughts on all of this.
