Buoyed by the success of my experiment photographing my left hand, I did a bit more reading and found plenty of information online on how to do focus stacking in Photoshop. Focusing stacking is a technique where the in-focus bits from a set of images can be combined into one image, giving the appearance of greater depth of field.
To begin, a set of images of the same subject and same composition need to be taken and selected in Adobe Bridge. These need to be opened as one layered image in Photoshop. To do this go to Tools -> Photoshop -> Load Files Into Photoshop Layers.
Depending on how fast your computer is and how large the files created by your camera are, this can take quite a while. Once all the layers have loaded up, they all need to be selected. Simply click the top layer, hold shift, and click the bottom layer to select them all.
Now you have all your layers selected, you can get Photoshop to automatically align and merge your layers into one image. To align the layers, go to Edit -> Auto Align Layers and ensure Auto is selected in the Projection option. Aligning you layers may take a while, depending on file sizes and how misaligned each image is.
Finally, to complete the focus stacking select Edit -> Auto Blend Layers. Make sure that Stack Images is selected and that only Seamless Tones and Colors is ticked. Again, this process can take a while, but it should be worth the wait. After a few minutes, you’ll be greeted with an image with much greater depth of field, and clarity than you may have been able to get by stopping down the aperture of your lens. However, some blurry bits often need cropping from the edges after stacking is complete.
Here are some some examples of my first attempts playing with this technique:
To make the process easier, I created a Photoshop action, which allows me to simply open the set of images as layers in Photoshop, select all the layers and click play on the actions palette. As both the aligning and stacking processes can take a fair while to complete, this frees up time to make a warm beverage of you choice. A copy of the Photoshop Action can be downloaded here.