Battery Checker
A battery checker is a great tool to have on hand if you are using
AA or whatever batteries. I carry one in the car.
Light Uses
I don’t have to point out that lighting is crucial to photography and
focus stacking just ups the ante. It can be hard in a semi-cloudy
day to get consistent light across a set of ten or twenty photos. As
the light changes it affects each layer in the stack.
If you want to really understand lighting get a feel for lighting as
done with video, like movie lighting. There is no difference in light
between still photography and movies, only budget. A movie set,
indoors or out, cannot afford to screw up the lighting, and video and
film eat light. Movies have to be well lighted and even a little study
of their methods is enough to point out that it is all about the
lighting.