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 1

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.

Answer 2

A non-obvious answer is to increase the light. Because macro photography has such a small depth of field we're often forced to balance the aperture setting with avoiding camera vibration.

Adding some off-camera strobe will nicely fix both problems. The burst itself will act as the shutter if you want it to, by getting about 5-6 stops between the flash output and your ambient light, completely ruling out vibration problems. Even a long duration burst will be a lot faster than you can get with a macro without supplemental light.

Also, you can change your aperture to f18 or f22 with enough flash, extending your macro range as far as possible.

John Shaw shows some adapters he used in his landscape and macro books, also you'll see samples of macro work on the strobist site where people have used small flashes to get great results.

Answer 3

Macro focusing can be a difficult task, even with the proper tools, as DOF can be so thin (sometimes just millimeters thick, or with extension tubes, even thinner.) There are a couple techniques you can use to focus at extreme macro scales. The cheapest, and obviously the simplest, is to move the object if it is mobile. You can usually get a very fine degree of control over where your focal plane ends up.

In the event that you do not have the ability to move the subject, and moving the camera is the only option, a Macro Focusing Rail is the best option. A focusing rail is either a stand-alone device, or often a specialized tripod head, that mounts the camera and allows very, very fine control over your camera-to-subject distance as well as vertical camera height. A decent macro focusing rail is the "Adorama Budget Macro Focusing Rail Set with 4 Way, Fine Control, Camera Focusing Rail for Macro Photography". It costs about $70. If you want to have the maximum level of control, higher build quality, etc. B&H has an entire category full of macro focusing rails. Prices range from about $90 to several hundred dollars.

A macro focusing rail will really change the way you do macro photography. Once you have a smooth, multiplanar way to very finely adjust your focal plane, extreme close up macro photography where your DOF is millimeters (or less) in thickness becomes much, much easier.

Finally, if you want even more control over your focal plane, you could try using a tilt/shift lens. I am not sure which brand of camera you use, however Canon makes the TS-E 90mm f/2.8 lens. This lens has additional tilt, shift, and rotate controls that give you far more control over your focal plane than standard lenses. Combined with a few extension tubes, the TS-E 90mm lens becomes a great macro lens that allows the focal plane to be adjusted, allowing you to bring the maximal amount of your scene into focus without the need to make extremely fine adjustments using a focusing rail. A focusing rail will still be helpful, however getting clean focus with a tilt/shift lens like the TS-E 90mm can change the way you do macro photography. Hartblei makes some tilt shift lenses that can be used on a variety of camera bodies.

Answer 4

In addition to @jrista's detailed answer, you may also wish to experiment with focus bracketing. This technique involves taking many photos of the same macro scene with many different focus points, and then composing a final, fully-in-focus-image from the images. I haven't done it myself, but I imagine that it could be a very useful technique for your problem.

Answer 5

Another off-a-bit idea would be using tethered capture (NKRemote is what I use for my Nikon D5000) and visualizing the live view on my laptop 15" screen instead of the 2.5" screen on the camera. Using manual focus I can then gently adjust the focus until I'm satisfied.

Answer 6

From my experience the easiest way to do this is moving the object while looking in the viewfinder.