Macro-Cage

Build your own Macro-Cage…

Back in 2019, I interviewed Queensland Museum Network’s Collection imager, Geoff Thompson, who was kind enough to share a quick overview of his approach to focus stacking. Geoff started out as an entomology illustrator but embraced digital imaging in the 1990s and now uses a bespoke focus-stacking rig built around a fine-threaded stepper-controlled rail that enables him to stack with micron level accuracy. His work is world-class.

Cairns Birdwing Butterfly. Dorsal view of a male Ornithoptera euphorion. Canon 5DS, 100mm macro at 1:2X. Focus stacked from 5X16 source images with Zerene Stacker software. Merged from 5 stacked images with Photoshop. Further edited with Photoshop and Topaz AI software. © Queensland Museum, Geoff Thompson.

I conducted some simple tests with manual focus-stacking (moving the camera by hand) and processed a number of stills manually in PhotoShop to convince myself that this might be a viable technique to add to ScanCave’s repertoire. Of course, Geoff is working in 2D, not attempting photogrammetry, so his image count is significantly lower and while this process did look promising, clearly you would be insane to attempt it without the aid of some automation.

Manual stacking test of First Nation’s stone tool…
LEFT: Single Image from stack (rear of object is soft) RIGHT: Stacked image.

Thanks to generous support from the Australian Research Data Commons we had funding available and opted to acquire a Stackshot system by Cognisys – ordering a three axis kit (two rotary tables plus threaded rail). This section describes how to build various types of macro cage for supporting the elements needed in an effective focus-stacking rig – camera, lights, specimen’s, background etc.

This next example has nothing to do with focus-stacking but it’s a cool model…