Today’s Post by Jason Anderson
Focus stacking is mostly used macro photography, where intricate detail is needed across a range wider than what the aperture will normally allow. 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’re layering. In HDR images, you are compositing images with different exposure values over one another. In focus stacking, you are changing 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.
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’ll have shallow depth-of-field, which causes the blurred background. To bring the rest of it into focus, I need to “stack” more shots that have a different points 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, with Helicon Focus becoming pretty much the industry standard. Their quality of processing is 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.