Problems of Long-Focus Photographic Astrometry
A survey is given of astronomical problems utilizing the techniques and methods of long-focus astrometry, and of the sources of errors and the currently attainable accuracy in this field of applied optics. Particular attention is paid to the astronomical problems of parallax and orbital motion, to errors due to atmospheric dispersion, and to the astrometric effects of coma, if present in an achromatic objective. A brief outlook follows on current progress in techniques and future expectations.