A Primer on Focus Stacking
Special guest post by Jason Anderson
With all the talk and hoopla over things like dynamic range, HDR, Megapixels, and the latest and greatest bells and whistles in photography, some of the staples in composition are often over-looked. Focus stacking is one such area. Most folks kind of look at me quizzically when I bring this topic up, primarily because it is rather niche and unique, but it does rely on principles of composition that have been around for a while.
Focus stacking is used mostly in genres like macro photography, where intricate detail is needed across a range wider than what the aperture will allow for during composition. The principle is much like the layered approach to HDR imagery – where you stack layers of images with different compositions on top of each other and blend the right portions through the entire image.
Where focus stacking differs from HDR is the types of images that you are layering. In HDR images, you are compositing images with different exposure values over one another. In focus stacking, you are not changing the exposure values, rather just the point of focus. As depth of field drops off both in front of and behind your focusing point, the subject will blur. While this may be an appreciated blurring technique in some cases, in other cases, getting different depths of field from different focusing points can make for a tack sharp macro throughout the range of the subject.
As is most often the case, explaining a photography concept is best done with images, so let’s take a look at an example. For easy demonstration, I took a white cordless phone and placed it on a black background. This way color issues are kept to a minimum…
Notice on the first focusing point, the sharpest point is right near the front? It also quickly drops off into the background as I was shooting at f2.8 The low aperture number means I will have a very shallow depth of field, which is what is causing the blurred background. To bring the rest of it into focus, I need to “stack” more shots that have a different point of focus. So, let’s add another few to the composite:
The end result from stacking all these together can be accomplished by any one of a number of methods ranging from the most time-consuming of doing it manually inside Lightroom or Photoshop, and the most efficient one of using 3rd party software. While several options do exist, the one that has become pretty much the industry standard is that of Helicon Focus! Their quality of processing is, bar none, among the best I’ve seen.
In the meantime, here’s the result (at right) of an image that has been focus-stacked:
Visit Jason Anderson at his blog “Canon Blogger” for more tutorials, articles, and photo nuggets.