Evaluating differences in soil appearance from field to photographs to aid in developing soil profile photography guidelines

Scope and method of study. The purpose of this study was to (1) evaluate the effect that changing the chosen factors and conditions has on soil appearance in photographs, (2) evaluate color difference using comparisons between spectrophotometric measurements and visual measurements, and (3) develop soil profile photography guidelines. Nine factors (film, distance from lens to soil profile, soil profile surface moisture, camera settings, filters, angles, time of day, night photography (using artificial lighting), and color matching) suspected to affect soil appearance in photographs were studied. Soil profiles representing two soil series (Teller and Grainola) were photographed using a Graflex Crown Graphic large format camera with a 150 mm lens. Distinguishing features and characteristics obtained from field description sheets for each soil were compared to the photographic prints for each factor. Comparisons were made to determine if the chosen factors affected the ability to distinguish each soil's observable attributes. Spectrophotometric measurements were taken of both a 22 x 28 cm Munsell color sheet and the prints containing the same sheet.; Findings and conclusions. All factors affected overall soil color. Use of different films affected the ability to clearly see key soil features. Porta 160 NC film most accurately represented the two soils. The distance that captured the soil solum plus 25% of the soil solum depth was chosen as the best distance that would allow viewing all the soil's attributes. Water sprayed on the soil profile affected how pronounced the soil features appeared. Aperture and shutter speed settings as well as filters affected the clarity of features. A 90° angle between camera lens and soil profile resulted in no distortion of features. The time of day chosen affected shadowing on the soil profile. Photographs taken at night using artificial lighting most clearly expressed the features and characteristics of both soils. Color matching to a standard resulted in accurate representations of soil color. Spectrophotometric results indicated that photographs of soil profiles are redder in hue than the soil the photographs represent. Spectrophotometric measurements did not consistently agree with visual measurements. Soil profile photography guidelines were suggested.