Continuing on the macro tips from this week, here is another for how to control your depth of field outside of adjusting your f/stop. When you are composing your image, pay attention to the relative angle from your camera (more specifically, the camera plane) vs the subject. You will gain the most depth of field, when the camera plane is perpendicular to the subject, instead of off to an angle. The concept is similar to how the sky changes colors in the morning and evening. This is because the light has to pass through a greater layer of the atmosphere during that time, distorting the color. (And why the mid-day sun is so bright and powerful vs the breaking dawn or setting sun.) For those who are amateur astronomers, the same concept applies when looking out into space. Looking up overhead will always provide the clearest view over looking at something close to the horizon. Again, this has to do with the amount of atmosphere the light has to pass through.
So by keeping the camera plane perpendicular to the subject, you minimize the distance light has to travel, and with macros, that can make a huge difference!