Commonly, when we think of close up images we envision filling the frame with subjects the size of a butterfly. When we think of macro, that subject size becomes smaller by a factor of five or so. That might be a small beetle or maybe a fly. There is a vast world that is much smaller that is worthy of our photography prowess. That is the world of ultra macro or indeed micro photography.
There are many tools used for life-sized images. The macro lens, extension tubes, bellows attachment and even microscopes. Each has its advantages, disadvantages and limitations. Some of the major considerations when doing image capture at magnifications vastly greater than life-size include, image resolution, focus, depth of field, lighting and vibrations to name a few. The micro world is a challenging one indeed.
The above image is the head of a bee. It is magnified about 1.6 times on the sensor. This is not a very great magnification, but in order to capture sufficient depth of field in this image 53 individual images with a different point of focus from the antennae to the rear of the head were made. Each image was spaced 0.005 inch from one another from the front to the back. These multiple images spanned the overall distance of o.265 inch.
Image making like this calls for a stable specimen and camera platform, precise and uniform movements in focus and absolutely uniform, clean lighting. In order to accomplish this a bellows and true macro lens was used with a micrometer specimen stage and electronic flash. All this apparatus may create a big problem: movement through vibrations. This really reduces image resolution.
To overcome the problems, I am assembling a specialized piece of equipment to enable the precision required. This is my work in process. The idea is not new, per se, but getting all the pieces together has been interesting. It looks like this:
This micro set up is designed for versatility and for use from magnifications of 1:1 or life-size on the sensor with a 55 mm macro lens to magnifications of close to 40:1 with a true microscope lens on the bellows.
Camera movement is facilitated by a geared linear positioner with provisions for a stepper motor, an Arca-style plate on the positioner table and the focusing rail of the Nikon PB-4 bellows.
Subject positioning is possible in all three X, Y, and Z planes. A cannibalized AO microscope stand provides coarse and fine movement in the vertical direction. A linear motion micrometer stage provides movement in X and Y directions. The specimen is held by an articulating holder mounted on the linear stage. (See Variable macro specimen holder) This holder will facilitate the use of pinned insects in addition to other larger materials fastened to the stage itself.
All this assembly is mounted together on a platform to reduce independent vibrations. The weight is substantial, providing additional aid in mitigating vibrations. While the current prototype mounting base is dimensional lumber, future refinements include an all-metal positioning table and the addition of a stepper motor for automating focus stacking.
The clean design without bulky tripods and other equipment in the way allows the use of SB-800 or SB-910 electronic flash on articulated arms in a unobstructed manner.
A future post will visit images made in much greater magnifications. Improvements to image resolution will be measured and discussed. Stay tuned!