How to micro-adjust distance for focusing in macro photography?

Question

I'd like to take macro photos, but I have a problem with the focus.

I put the object on a (light) table, I put my camera on my tripod and take a few shots. Since the depth of field is very small usually I realize that I have to change the distance between the object and my camera. Changing this distance is quite difficult if I have to put my camera 0.5mm closer. Is the a way to easily (and continuously) change this distance? Is there a tripod accessory for this?

I use a reverse ring and a prime lens, but the question probably applies for other types of macro photography.

Answer

In this sort of situation, the normal approach is to use a focusing rail which allows fine and controlled adjustments to be made. There are several available on the market, with some under £50, but it would be possible to make one yourself, if you have the right tools.

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