While new to the Arduino forum, I've been an avid Arduino fan for several years now. Using it, I have been able to bring together three of my favorite hobbies: photography, programming, and electronics.
Using Arduino, I have built an automated "focus stacking" controller. This is for high-magnification macro or microphotography. What it does is incrementally move a platform driven by a stepper motor, holding either the camera or the object being photographed, while simultaneously controlling the camera's shutter. The result is numerous photographs at evenly spaced sequential focus points, which can be combined using software into a single image with extended depth of field. It can also be used to make 3d representations of an object using a single lens. This technique is not new, and commercial products exist to do this. A plethora of similar hobbiest projects also exist, but many are based around solderless breadboards, jumpers, and seem to be prototypes rather than finished products. I wanted to document a project meant to look more professional (and not get you into trouble with airport security), as well one that I think leaves plenty of room for expansion into other realms (time-lapse photography, driving equatorial mounts, and so on).
The project is intended to work with a large variety of two-phase bipolar steppers that draw about 300-800ma when both windings are energized. Technically, the quad half-H bridge chip can drive more powerful steppers, but heat will become an issue, necessitating better airflow (rather than the closed case I've used here). It also should work with any digital camera on the market that has a three-conductor shutter release port (that is the vast majority of digital SLRs).
I intentionally avoided motor shields. I have my long list of reasons, but in general, I was happier with a single inexpensive quad half-H-bridge chip that I can much more easily wrap my head around.
It is a pretty sizable document, so rather than paste it here, I will direct you to the article on my website (no ads, no products being sold, I make no money from it): http://www.ryleeisitt.ca/articles/building-a-focus-stacking-controller/