fotografias tomadas por nikon macro lens

Modern microscopes deal with field curvature by correcting this aberration using specially designed flat-field objectives. This objective is the obvious choice for optimum results in photomicrography. Figure 2 (b) illustrates the case of an objective that has been corrected for curvature of field aberrations. This would be the focus that a microscopist would be forced to use for photomicrography with optics in this state. The bottom image (c) in Figure 2 shows the section with the central portion of the viewfield in focus and the edges blurred. Notice that the central portion of the image is very blurred and it is not possible to distinguish any minor structural details present in the specimen. The upper image (a) in Figure 2 shows the thin section with only the edges in focus. This concept is illustrated in Figure 2 using photomicrographs of a stained thin section of an elephant toe bone.

However, for photomicrography, field curvature can be a serious problem, especially when a portion of the photomicrograph is out of focus. It is a simple matter to use the fine focus knob to correct small deficiencies in specimen focus. Normally, this is not a serious problem when the microscopist is routinely scanning samples to observe their various features. When the image is viewed in the eyepieces (oculars) of a microscope, it either appears sharp and crisp in the center or on the edges of the viewfield but not both. The image can be focused over the range between A and B to produce either a sharp focus on the edges or in the center.

Fotografias tomadas por nikon macro lens