COUNTRY SCIENTIST

BY FORREST M. MIMS III

Doing Science

With a Digital Scanner

The transition from film to digital cameras has made a huge impact on how amateur scientists can save, analyze, catalog, and publish their imagery. It’s safe to say that digital cameras and personal computers are among the most important tools in the amateur scientist’s kit.

When the subject is two-dimensional, flatbed digital scanners can also play a major role in imaging science. They are ideal for making high-resolution images of leaves, dragonflies, butterflies, tree ring sections, soil samples, and many other subjects.

Advantages and Disadvantages of Scanning

Virtually shadow-free lighting is a key advantage of a digital scanner, for the scanner provides its own light source. Another advantage is that scanners don’t suffer from the distortions caused by camera lenses. Scanners are relatively inexpensive, and they can be used for many applications beyond the scientific roles described here.

Besides their two-dimension limitation, a major drawback of scanners is that objects being scanned must fit within the scanner’s image plane. Scanners are also much larger than digital cameras.

Background C olor

Most objects that I’ve scanned looked best with a white background. Because my scanner (HP Scanjet 3970) has a 35mm slide scanner slot built into its lid, it’s necessary to cover the object being scanned with an uninterrupted background. Two or three sheets of white 20-pound paper work well.

Light-colored objects are not easily visible when scanned against the white background of a typical scanner lid. To provide contrast with light-colored objects, place black construction paper over the object being scanned before closing the lid. You can use various colors for special effects.

How to Scan Dragonflies

For years I have photographed dragonflies and damselflies by quietly sneaking behind them. With

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practice, it’s possible to get within a few inches of some species. While real-world images like these are important, entomologists Forrest Mitchell and James L. Lasswell of the Texas AgriLife Research and Extension Center at Stephenville, Texas, have used digital scanning to create an impressive library of top and side views of many dragonflies and damselflies. You can see these images online at Digital Dragonflies ( dragonflies.org).

The images at Digital Dragonflies were made by cooling each specimen in a refrigerator to keep it still while it was being scanned. The insects were then placed backside down on the scanner’s glass bed. They were protected from being crushed by the scanner’s lid by placing them inside a 10cm×12cm rectangle cut in a mouse pad (see their website for details). The mouse pad approach is probably best, but I’ve found that ordinary corrugated fiberboard will also work.

Based on my experience scanning dragonflies (Figure A), it would seem that butterflies and moths could also be scanned. A severe drought has slashed the butterfly population in Central Texas, and I’ll try this method as soon as the butterflies return.

Fossils and Artifacts

Fossils and artifacts having a flat surface are easily scanned. For example, I’ve scanned the fossil of a trilobite with good results (Figure B). Even ripple marks in the mud (now shale) on which the creature was resting were captured.

Years ago I found a flint artifact in the gravel bottom of the creek that borders our land. The artifact is a flint scraper that is very flat on both sides, and it was easily scanned against a white background (Figure C). Flint arrowheads and spear points can also be scanned.

Plants

The leaves of many kinds of plants are easily scanned against a white background (Figure D). The main limitation of scanning leaves is the size restriction posed by the scanner’s bed.