The Dragon Wagon

The Dragon Wagon
The landscaping changes often.

Tuesday, March 2, 2010

Focus Stacking

One of the problems doing macro or close-up photography with a DSLR is a very shallow Depth-of-Field (DOF).  Depth-of-Field is the range of distances from the camera that the image has an acceptable sharpness of focus.  One way to increase the DOF is to close the aperture of the lens (stop down) significantly.  There are a few problems with small apertures though.  First, all lenses have a minimum aperture that they can be set to.  Second, very small apertures require significantly longer exposure times.  Third, very small apertures can suffer from a loss of sharpness because of a property of light called diffraction.

With digital images and computer processing, there is now another option called "Focus Stacking".  This involves taking a series of images, with the camera focused at different distances from the camera.  Each image will then contain a version of the scene, with a part at a different depth in sharp focus.  These images are then submitted to a computer program that isolates the part of each image that is in sharp focus and then merges these together into a single image which is all (or mostly) in sharp focus.  There are a number of such programs available, from free to commercially sold.

Here is a small experiment that I did with a free program called CombineZP.

First I took a series of images at different focus depths.  Below are five images out of that series.

These files I used in the program CombineZP, which generated this resulting file.


Finally, I took the above image into Photoshop and cleaned up the background to yield this final image.