Adapting a Short-Bellows, Roll-Film Kodak for Detail Work in the Field

Abstract

Most geologists, when in the field, have occasionally felt the need of a portable camera with which they might take large-size detail photographs. The ordinary equipment for such work, the long-draw, box camera, is far too heavy and bulky to be carried by the geologist as a part of his daily accoutrement. The roll-film kodak with the customary short bellows which is most convenient for his usual needs, fails when he wishes a picture larger than about one-tenth natural size, and the auxiliary portrait lens does not greatly increase the scope of his outfit. If he wishes a detail picture of a fossil in place, a curious marking or texture of a rock which cannot be conveniently sent to his headquarters, he must note the place and come again later with the more bulky equipment. He almost never does. The device described below has been found by the writer to be a simple and convenient solution of the problem. An auxiliary portrait lens was first secured to fit the kodak he wished to use. This attachment consists of a simple plano-convex lens of about 52-inch focus. When placed close in front of the kodak lens this causes parallel beams of light to become slightly convergent when they strike the main lens system and thus shortens the focus of the combination (See Fig. i, Scale II). With the principal focus now somewhat nearer the ground glass, the slight additional excess of bellowslength permits focusing on closer objects and hence larger pictures than with the kodak lens only. Next, there were procured from an optician two more lenses of foci approximately 16 inches and 8 inches respectively. These were ground to the proper diameter to fit the cell belonging to the original auxiliary. The three lenses are readily interchangeable by unscrewing the ring which holds in place the lens used. By using

Carbon, Metals, and Grain Size Correlate with Bacterial Community Structure in Sediments of a High Arsenic Aquifer

“…Sediments were freeze-dried for 48–72 h and then oven-dried at 60°C for 48 h. In order to disaggregate the sediment, we suspended samples in distilled water for 24 h. Then we passed each wet sub-sample serially through 150 and 63 μm sieves. Sediment fractions were dried and weighed and grain size distributions were reported as percentage sand (i.e., greater than 150 μm in diameter), silty-sand (between 150 and 63 μm in diameter), and silt (63 μm in diameter and smaller; Wentworth, 1922). In the statistical analyses we included data from only one grain size class, percentage silt, since percentage sand, percentage silty-sand, and percentage silt were strongly autocorrelated.…”