Why horizontal field width?

Abstract

AbstractUse of field width rather than “magnification” as an indicator of scale gives the advantage that the caption to an illustration does not need to be changed if the magnification is changed for technical reasons during the printing process. The commonly used “micron bar” has the same advantage, but it is argued here that the use of a linear scale marker encourages the tendency to measure features from a single projection of the object. Most scanning electron micrographs portray rough surfaces, and linear distances need to be computed from stereophotogrammetric measurements. Our opinion is that micron bars should only be added where they can be used in a valid sense to make measurements. Stating the width of the field of view scanned in an SEM image gives an adequate idea of scale, without implying that one may proceed to derive accurate measurements without more elaborate procedures.