This first project was something I'd been wanting to try out for years: to combine several pictures of the same scene, with different focus ranges, to create a single picture with extended depth of focus. This is common practice in ultrasound imaging.

Here the camera sat on a small garden table, with some recently fallen leaves from a "Festival" Liquidambar tree (so named because it produces leaves with a variety of fall colors). About four yards behind the garden table is a mask on the trunk of the tree, and about a dozen yards further back sits a garage. Using Adobe Photoshop to extract and combine the sharpest parts of six different images was tedious, but the result demonstrates how well the technique can work, and some of its pitfalls. One such pitfall is that objects can end up with a halo around them from their unfocused counterpart.

One day I would like to try automating this process. The first part would be to have software determine automatically what F-stop to use (based on the desired sharpness), and how many pictures to take and to what distance each should be focused (based on the F-stop and the desired uniformity of sharpness). If you look closely at the leaves and the grain of the wood in the garden table you'll see that the near-field foci were spaced too far apart in this experiment to get uniform sharpness. Although this isn't easy to get right by hand, it wouldn't be very difficult to write software to compute the optimum settings.

Automating the combining of the pictures seems like the hard part, but maybe the camera could help by using its auto-focusing apparatus to record which parts of each picture are in focus. A product called Helicon Focus combines pictures without this information and appears to do an excellent job.

I've used the technique of combining different pictures of the same scene many times now, sometimes to extend the range of focus as here, but it can also help in scenes that combine very light and very dark regions that are both rich in detail. For example, in this photo, the sky and the ground are from different exposures.

This "Frog Princess" immediately caught my eye as I walked into the Gilbert Bayes Sculpture Gallery in the Victoria and Albert museum. When I noticed her shadow I just had to try capturing this scene with my new digital camera. Unfortunately, it was dim inside, the exposure needed multiple seconds, and I did not have a tripod. I ended up taking four exposures with the camera braced against a convenient display case. They all came out blurry except for this one.

As you can see in the first picture here, in spite of the long exposure the princess herself came out too dark. Unfortunately, lightening the whole image resulted in washed out walls and a less interesting shadow. So this needed a princess-shaped mask in Photoshop. Getting the boundary between the lightened princess and the unlightened walls to look natural was very tricky -- the mask had to be just the right size and shape, and to have edges that were feathered over just the right number of pixels. I'd be embarrassed to admit how many hours I spent on this, and how many false starts were abandoned as I learned Photoshop. But I really came to love this work of art, and will no doubt revisit the V&A museum the next time I'm in London. I often wonder if her shadow was the artist's intent, or a lucky accident discovered by a lighting designer at the museum.