Although many macro photographers shoot by hand using a lot of dedicated equipment, there an equal number that shoot macro in the studio using small light boxes and an equal amount of special equipment to make, what many say, a difficult endeavor, easier.
Of the many little problems encountered in macro photography, is accurate focusing. The depth-of-field (DOF) narrows as the magnification goes up therefore, having control over how one focuses assures better macro images with better DOF. Auto-Focus is certainly a valid way of focusing however, automatic digital cameras often focus on a nearby spot of the subject rather then on the intended only to re-focus when the shutter is pressed often moving the focus zone.
Often, it is required to focus slightly past the point of intend relying on the available "front" focus to get point of intend in proper focus in the beginning of the focus field thus creating a useable DOF. This kind of focusing can not be obtained using automatic focusing other then with luck and manual focusing is the only answer left.
A camera with a close-up lens mounted on a tripod with a device allowing in/out camera adjustment in fine increments is needed to "nail" the best point of focus and the associated DOF. Such a device is called a 'Focusing rail" and is located between the tripod and the camera.
There are two types and a number of manufacturers to choose from and all have a common problem in that they are expensive. Single movement focusing rails are cheaper than bidirectional units where bidirectional units have the ability to move sideways providing for better framing/positioning.
Recently I purchased, via Ebay, a "4-way," black iodized focusing rail marketed by LinkDelight a photographic accessory retailer located in Honking, China. This unit has a ten centimeter total bi-directional movement (five centimeter both sides of the central axis) and seems well made from cast and machined aluminum. Slide adjustments is achieved through microscopic rack and pinion mechanisms actuated by knurled knobs and setscrew type slide locks to prevent slide movement after adjustment. One full knob rotation equals about 3.5 cm linear movement. Knob backlash is about 1/16 inch yet, head movement of one mm is indeed possible.
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| 4-Way Macro Focusing Rail Slider for D-SLR Camera |
I found the unit well made and functional without play and rock in the slides yet, the price as advertised by Ebay is only $ 57.00 and $ 62.00 directly from www.linkdelight.com. This same unit is advertised by a well known mail order house for $ 176.00 plus postage making this an excellent buy.