High Depth of Field Microphotography
One of the limiting factors in producing images of insects is the low depth of field possible with light microscopy, at the magnifications required. Scanning Electron Microscopy (SEM) is sometimes used but it places the specimen at risk and cannot show colour pattern or a natural appearance.
In recent years high depth of field computer imaging systems have become available. Automontage is the best known. The operator focuses at the top of the specimen and then takes a series of digital photographs; each one focused further down than the last, until the lowest levels of the visible parts of the specimen are in focus. These are the source images and there may be between 20 and 40 of them. The software program then lines up the images before combining all the sharp elements of the series of photographs into one image.
Recently Automontage Essentials software came on the market for about $1500. The Entomology team at the Queensland Museum was able to purchase a manual system, added on to an existing microscope.
Single Image | High Depth of Field Image |
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Despite being of great use these high depth of field photographs still have limitations when compared to illustrations. Insects die with legs curled up and in twisted positions, sometimes with lost legs or other appendages, and the diagnostic features that need to be shown are often difficult to see. The illustrator twists and turns the specimen under various lighting conditions, emphasises important features and straightens out the appendages so that their measured lengths can be compared without foreshortening.
Out of focus structures can obscure lower structures with their blurred edges and the program does not handle out of focus backgrounds well. Both of these problems can produce a pattern of dark lines that can detract from the overall appearance of the montage image and interfere with important visual information. Some of these problems can be overcome by digital editing using features of Automontage.
Further refinements can be made using digital illustration programs to produce three dimensional images of specimens. View the wondrous world of insects using 3-D glasses to gain an insight into an insect's perspective.