This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Compound Eye has been quiet of late. My silence is for a good cause, though! The past few months have been hectic as I transitioned from freelance photography in Illinois to a new job: Curator of Entomology at the University of Texas in Austin. The move has meant a blogging hiatus.
My new academic digs do not mean an end to photography, just in case you thought you'd finally be rid of me. Far from it! Scientific imaging is integral to modern museum curation, and the first project I undertook on arrival was to build an inexpensive imaging system for the UT insect collection. Specifically, we needed something capable of focus-stacking tiny subjects for artificially extended depth of field. Our modest budget of $6k was enough for a rig with the flexibility to capture insects from the size of a large butterfly down to the scales on their wings.
The essence of the rig is simple. It's a standard digital camera with macro lens, mounted on a Cognisys motorized focus rail, bolted to a copy stand. The camera is tethered to a computer, and the images are processed using common focus-stacking and image editing software. The contraption can be built in a day from off-the-shelf parts and looks like this:
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Should you wish to make your own, I have listed the components and their prices below.
Camera and lenses
Canon EOS 7D dSLR: $1,099
Canon MP-E 65mm 1-5x macro lens: $1,049
Canon 100mm f/2.8 macro lens: $599
Kenko Extension Tube Set: $129
Lighting
3 Yonguo 560 III flashes: $71/ea
Cowboy Studio NPT-04 wireless flash triggers: $40 for 1 trigger/3 receivers
2 Clamp lights with bulbs: $10/ea
Roscolux Tough White Diffusion: $7
Support
RPS Studio RS-CS1070 Deluxe Copy Stand: $170
2 basic ring stands: $13/ea
Motorized focus rail
Cognisys Stackshot extended rail: $625
Canon N3 shutter cable: $39
Computation & Software
Dell Precision T1700 Desktop Computer: $647
Dell UltraSharp U2412M LCD Monitor: $269
Adobe Lightroom: $140
Zerene Stacker Pro: $289
Canon EOS utility software: free with camera
Miscellanous accessories
Eneloop rechargeable AA batteries (for the flashes): $43
Eneloop battery charger: $17
16 GB Compact Flash memory card: $42
Lens cleaning kit: $11
1/4-20 bolt with nut & washers: $1
Total cost: $5965
Assembly Instructions:
1. Set up the copy stand.
2. Hold the StackShot rail in the lowest position on the copy stand's post and mark the position of the center thread on both the front and back of the post.
3. Remove the StackShot and drill holes in the post using a 5/16" bit or slightly larger.
4. Bolt the StackShot to the copy stand through the holes. Use washers on the far side to ensure that the bolt doesn't protrude enough to impede the StackShot carriage's movement.
5. Place the computer and monitor within a standard USB cable's length of the copy stand.
6. Install the imaging software and the EOS utility software on the computer.
7. Set up the camera per the manufacturers' instructions with a charged battery, memory card, and menu settings as you prefer.
8. Mount the lens on the camera, and mount the camera on the StackShot rail. If using the MP-E lens, for balance use the MP-E's collar mount rather than the camera's tripod mount.
9. Connect the camera to the computer with a USB cable.
10. Connect the StackShot controller to its power supply, the computer (USB), the rail, and the camera (shutter cable), following the manufacturer's instructions.
11. Set up the ring stands and clamp lights to illuminate the area under the camera.
12. Mount the flash trigger on the camera's hot shoe and the three flashes on the wireless receivers.
13. Make a light diffusion cone from the Roscolux tough white diffusion, place it under the camera, and set the three flashes on stands around it.
14. The system should be ready for testing!
Operation beyond mere assembly is a rather more complex affair, and one I will leave for future posts. To make the most of the system, you'll need knowledge of SLR photography, flash photography, focus-stacking, and image processing. The many steps may be a bit much at first, so new users should expect to suffer through a few sessions before producing workable images.
The rig here is $6k, but a refurbished camera tethered to existing computers running free software (I recommend Combine Z for free stacking), drops the tag under $3.5k. A budget of $10k will buy a more powerful computer, a larger monitor, an additional lens, and a camera with a full-frame sensor. What's more, since the system is built around a stock SLR, the camera can be detached from the rail for general purpose photography.
The proof is in the image pudding, of course. Check out these sample shots from the UT system's first week of operation. I don't know about you, but I'm pretty pleased with these.