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Botanical Photography - Digital Imaging, Lenses, Tripods and Supports, Light Sources and Reflectors, Filters, Backgrounds, Camera-free Photography

plant plants focus color

PAUL HARCOURT-DAVIS
Professional photographer and author

In the purest definition, botanical photography is used to depict plants accurately with respect to their form and color, providing relevant information documenting plant morphology and function, the environment, plant life histories, diseases, the effects of pollution, and relationships with other life forms. Successful botanical photography, however, is much more than this. It is as much an art as well as a science and requires a detailed knowledge of plants and their habitats as well as a keen eye for a picture. It also poses technical challenges since it involves at least familiarity with a gamut of techniques from the photomicrography of plant parts and
microscopic specimens to satellite imaging showing enormous plant communities. Single plants and individual flowers demand the techniques of portraiture or macrophotography, while habitats can be photographed as wide-angle landscapes, complete with foreground plants. Most plant photography utilizes light in the visible spectrum but infrared-sensitive films and digital imaging can provide information about pollution, and ultraviolet light reveals striking flower markings—guidance systems for pollinators on apparently uniformly colored flowers.

The delicate colors, subtle forms, and textures of plants also inspire photographers in search of more “artistic” images, where limiting depth of field can be used to highlight details, and soft focus to create moods and the patterns within flowers or on leaves to form the basis for abstract images. Whether or not this usefully contributes to information about plants is open to question, but it surely encourages an appreciation of their intrinsic beauty.

Digital Imaging

Digital imaging is a boon to botanical photography in several ways. Small, largely automatic cameras can be used to obtain instant images of a plant site, complete with imprinted data as to time and exposure, and some digital SLRs can be coupled to a GPS system providing positional and altitude details. The color fidelity of color slide film has always been a problem with those materials of ISO 50 and below. The image’s blue color palette often suffered because of the tendency of some plant pigments to reflect infrared wavelengths invisible to the human eye but recorded on film. Even basic digital cameras now allow accurate tuning of the color through the white balance or later manipulation on a computer (provided monitors have been calibrated), especially if digital images have been recorded as RAW files. In the field, studio, or laboratory, the immediacy of digital imaging allows a photographer to make fine adjustments to color and composition and capture plant images that not only exist as records but are also more pleasing to the viewer.

Compact digital cameras have similarly made photomicrography much easier. Although the fixed lenses do not allow TTL focusing, a relay lens placed between the camera optic and a microscope eyepiece permits high-quality images to be obtained easily: video output from the camera to a monitor screen facilitates focusing and composition.

Lenses

Many wide-angle lenses on digital cameras have a useful close focus that allows a plant to be captured in its intimate environment. Using a small aperture to create greater depth of field also allows both plant and surroundings to be in focus within a wider landscape. The resulting accentuation of a foreground flower, for example, parallels the way humans tend to see plants, with the flower, literally, as the focus of the attention. Setting the subject at the hyperfocal distance for a particular aperture ensures everything from subject to infinity is in focus. But often the flower is just not close enough and precise focus of both distant landscape and the flower might only be achieved using the movements of a view camera or an SLR with tilt and shift lens. Fortunately, slight softening to infinity can accentuate the object of interest, producing greater impact with a still-discernable landscape to set the scene.

Moderate telephotos, whether zoom or fixed focus, can be used to reach otherwise inaccessible plants on ledges or tree flowers, for example. With long lenses, focus falls off quickly outside the plane of sharp focus, usefully isolating a main flower against a soft-blurred background. However, catadioptric (mirror) lenses often create doughnut-shaped highlights (a circle of confusion from a point light source or a specular highlight), which some users find annoying. This is particularly obvious with sparkling water shots or dappled foliage photographed against a bright sky. A wider range of images is possible if a close-up lens is added to the kit. Most of these focus to 1:1 (life size) without extension tubes and many utilize internal focusing: they also make excellent general portrait lenses for plants.

Tripods and Supports

The advice to use a firm tripod is as relevant now as ever. In the field or studio it is essential when using camera equipment at slow shutter speeds for any roll and sheet film or digital cameras. Modern carbon-fiber tripods are light and stable. Where weight is at a premium and there is no tripod available, photographers can make use of tree trunks, stones, walls, camera bags—anything to provide support and bracing. With digital cameras the effective ISO rating can be increased allowing shorter shutter speeds, but there is increased risk of “noise” in the final image. Telephoto lenses with electronic image stabilization give about two stops more tolerance to camera vibration when hand-holding.

Light Sources and Reflectors

Natural light is the preferred source by botanical photographers for color accuracy and a natural feel to the picture. Avoid direct sunlight where possible as it creates high contrast with hard shadows as well as exaggerated colors: A light “hazy” cloud covering is an ideal natural diffuser. Surprisingly, dull, rainy days are good for plant photography because colors are more saturated as a result of the even and flat illumination. When using film the lower levels of infrared radiation reflected by chlorophyll make blues easier to reliably record and the environment’s color temperature is higher which tends to emphasize blues.

Photographs of plants in the shade or with hard shadows can be improved by using portable, neutral-colored reflectors to soften and direct light where it is needed. Many prefer the warmer feel of light in early morning or evening, when the light is naturally redder. A digital camera with white balance set to cloudy or dull produces the same warming effect.

A flash system, used with care, can also produce excellent results where natural light levels are low. A fill-in flash with the flash set a stop or two below ambient light level improves color contrast. Exaggerated colors and harsh shadows can be avoided by using the built-in wide-angle diffuser available for many flash guns. The closer the flash is to the plants the softer the shadows will be since it acts as a broad light source. Major camera manufacturers and a few independent firms manufacture so-called “macro-flash” units with one or two small, relatively low-power flash heads that can be set at different intensities to vary lighting ratios for macro photography.

Filters

The ability to manipulate images in digital photography has made many color-balance filters redundant. However, a polarizing filter still has a place in any botanical photographer’s camera bag, though a “circular polarizer” will be needed with an auto-focus camera, some models of which are sensitive to the polarization of light. A polarizer is used to reduce reflections from non-metallic surfaces such as leaves and flowers, where it seems to intensify color. The effect is strongest at an angle of view of about 54 degrees (the Brewster angle) and is especially marked with reflections from still
water, where plant colors and other details beneath the surface are clearly seen. A polarizing filter also reduces glare and accentuates the blue of a clear sky, especially at right angles to the sun’s direction. This has to be used with care with fields of flowers to avoid unnaturally darkened skies.

Backgrounds

It is nearly impossible to find a colored background that is not obviously artificial. Black backgrounds can be very effective with plants and are a matter of taste and fashion. Black flock paper, obtainable from craft suppliers, offers the best true black but in close-up work black backgrounds occur naturally when any background is too far to be illuminated by the small flash guns used. Many photographers set plants against a neutral background and then use image manipulation programs to select and cut out flowers or plant parts and change the background as required. Great care in making the selection and feathering of edges is essential to produce a natural-looking result.

Camera-free Photography

A simple flatbed scanner can create a virtual digital herbarium, where specimens never fall apart or fade. To avoid squashing and distortion it is essential to lift the lid slightly above the specimen with supports and cover with a black cloth to avoid light seepage into the scanner. The effect is extremely good and many scanners have an unexpected depth of focus, high resolution, and well-modeled lighting, which are perfect for leaves and working well with flatter flower heads. This can often be a substitute for some kinds of close-up and macrophotography.

Some mistakenly believe that plant photography with its static subject material offers an easier form of nature photography than any other. In reality, it offers as many challenges as any branch of image-making and with the facilities offered by digital cameras, imagination is the only limit. Information capture in botanical photography is paramount, but no one need say “its only a record” as aesthetics are also important.

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