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Film distortion and accuracy of photographic registration of position
NOTES
FROM THE RESEARCH LABORATORY EASTMAN KODAK COMPANY.*
FILM D I S T O R T I O N AND ACCURACY OF PHOTOGRAPHIC REGISTRATION OF POSITION. 1 By F. E. Ross. THE results of the investigations by Schlesinger, Perrine, and Albrecht are summarized. In this investigation photographs of artificial stars were made with a precision camera reducing in the ratio of I to 20, on plates one inch wide pressed firmly against a rigid metal frame. In agreement with previous results, no evidence of systematic errors in distance was found, indicating that, in general, distortions are of purely local origin and extent. While the average measurements of ten exposures on a triple-coated plate are practically the same as for ten exposures on a thin emulsion, the local distortions are greater on the thick film. Yet the greatest variation from the mean was only o.oo44 ram. Faint and normal exposures gave the same average measurements within o.ooo 3 mm. Examination of the images showed that the effects of local variations in distribution of the silver bromide grains and of variations in sensitiveness and in development are negligible. Intensification modifies the minor details of image structure, but does not remove the larger irregularities in the original images nor change the centre of gravity appreciably, l~Ieasurements of the same plates, when wet and dry, agree accurately and indicate that, on drying, the images move perpendicular to the surface. However, this is not the case for images within a few millimetres of the edge, as these move outward on drying with alcohol or by hardening with formalin. It is concluded that the principal factor in producing the slight image displacements observed is local non-homogeneity of the gelatin. The probable error in accuracy of measurements of the position of stellar images is found to be considerably less in the case of plates with a fine grain thin emulsion (astronomical) than for those with thicker emulsions (Seed 3 ° and triple-coated). Intensification of weak * Communicated by the Director. ~Communication No. ~54 from the Research Laboratory of the Eastman Kodak Company and published in .dstrophys. J., January, I923, p. 33. 579
580
EASTI~IAN KODAK COMPANY NOTES.
[J.F.I.
images also decreases the error. In the foregoing measurements the probable error of a single setting was about o.ooo 5 mm. whereas displacement due to film distortion varied up to o.oo2 mm. as a m a x i m u m , but averaged only o.ooo 5 mm. for normal exposures on the thin emulsion. F o o d R e q u i r e m e n t s of M a n . r a T h e Food ( W a r ) Committee of the Royal Society has published a report on the food requirements of man and their variations according to age, sex, size, and occupation. On account of refuse and waste, the food as purchased should contain approximately ro per cent. more utilizable calories than are actually required by the individual. The energy requirement of a man varies with the work performed, and ranges from 250o to 50o0 calories daily; it may rise as high as 6o00 or even 8000 calories daily in exceptional cases such as the Canadian lumbermen in winter. The average working woman requires 2400 calories of energy daily; women engaged in sedentary labor, such as typewriting, require only I9OO calories daily. Brain workers require from 2200 to 2600 calories daily; their diet should be relatively high in protein. During exposure to low temperatures, extra energy should be supplied as protein (meat or fish) to those engaged in sedentary occupations, an6 as fat to those engaged in bodily work. Children under six years of age have 5° per cent. of the food requirement of an average man, those between six and ten years 60 per cent., and those between ten and thirteen years 83 per cent. of that requirement; those over thirten years of age require the same amount of food as an adult of the same sex. A growing child working with the same energy as an adult man requires approximately 200 additional calories daily. The diet of an average man should contain at least 7° or 80 grams of protein daily, a portion of which should be of animal origin. Milk should serve as a source of protein in the diet of infants and young children. The minimum amount of fat required daily varies with the race, from 20 grams in the case of a Japanese soldier to 75 grams in the case of people of British descent. From 35 to 40 per cent. of the total energy requirement of the body may be supplied as fat; those engaged in vigorous muscular work should receive at least 25 per cent. of their energy intake in the form of fat. A certain amount of fresh fruits or green vegetables should be eaten to supply the requisite vitamins. The diet should also include carbohydrates and salts. A condition of semi-starvation, with the food intake reduced to two-thirds its normal value, apparently can be endured for a period of several months without danger to health, but gives rise to a greatly reduced resistance to tuberculosis if extended over a period of several years. J.S.H.
FROM THE RESEARCH LABORATORY EASTMAN KODAK COMPANY.*
FILM D I S T O R T I O N AND ACCURACY OF PHOTOGRAPHIC REGISTRATION OF POSITION. 1 By F. E. Ross. THE results of the investigations by Schlesinger, Perrine, and Albrecht are summarized. In this investigation photographs of artificial stars were made with a precision camera reducing in the ratio of I to 20, on plates one inch wide pressed firmly against a rigid metal frame. In agreement with previous results, no evidence of systematic errors in distance was found, indicating that, in general, distortions are of purely local origin and extent. While the average measurements of ten exposures on a triple-coated plate are practically the same as for ten exposures on a thin emulsion, the local distortions are greater on the thick film. Yet the greatest variation from the mean was only o.oo44 ram. Faint and normal exposures gave the same average measurements within o.ooo 3 mm. Examination of the images showed that the effects of local variations in distribution of the silver bromide grains and of variations in sensitiveness and in development are negligible. Intensification modifies the minor details of image structure, but does not remove the larger irregularities in the original images nor change the centre of gravity appreciably, l~Ieasurements of the same plates, when wet and dry, agree accurately and indicate that, on drying, the images move perpendicular to the surface. However, this is not the case for images within a few millimetres of the edge, as these move outward on drying with alcohol or by hardening with formalin. It is concluded that the principal factor in producing the slight image displacements observed is local non-homogeneity of the gelatin. The probable error in accuracy of measurements of the position of stellar images is found to be considerably less in the case of plates with a fine grain thin emulsion (astronomical) than for those with thicker emulsions (Seed 3 ° and triple-coated). Intensification of weak * Communicated by the Director. ~Communication No. ~54 from the Research Laboratory of the Eastman Kodak Company and published in .dstrophys. J., January, I923, p. 33. 579
580
EASTI~IAN KODAK COMPANY NOTES.
[J.F.I.
images also decreases the error. In the foregoing measurements the probable error of a single setting was about o.ooo 5 mm. whereas displacement due to film distortion varied up to o.oo2 mm. as a m a x i m u m , but averaged only o.ooo 5 mm. for normal exposures on the thin emulsion. F o o d R e q u i r e m e n t s of M a n . r a T h e Food ( W a r ) Committee of the Royal Society has published a report on the food requirements of man and their variations according to age, sex, size, and occupation. On account of refuse and waste, the food as purchased should contain approximately ro per cent. more utilizable calories than are actually required by the individual. The energy requirement of a man varies with the work performed, and ranges from 250o to 50o0 calories daily; it may rise as high as 6o00 or even 8000 calories daily in exceptional cases such as the Canadian lumbermen in winter. The average working woman requires 2400 calories of energy daily; women engaged in sedentary labor, such as typewriting, require only I9OO calories daily. Brain workers require from 2200 to 2600 calories daily; their diet should be relatively high in protein. During exposure to low temperatures, extra energy should be supplied as protein (meat or fish) to those engaged in sedentary occupations, an6 as fat to those engaged in bodily work. Children under six years of age have 5° per cent. of the food requirement of an average man, those between six and ten years 60 per cent., and those between ten and thirteen years 83 per cent. of that requirement; those over thirten years of age require the same amount of food as an adult of the same sex. A growing child working with the same energy as an adult man requires approximately 200 additional calories daily. The diet of an average man should contain at least 7° or 80 grams of protein daily, a portion of which should be of animal origin. Milk should serve as a source of protein in the diet of infants and young children. The minimum amount of fat required daily varies with the race, from 20 grams in the case of a Japanese soldier to 75 grams in the case of people of British descent. From 35 to 40 per cent. of the total energy requirement of the body may be supplied as fat; those engaged in vigorous muscular work should receive at least 25 per cent. of their energy intake in the form of fat. A certain amount of fresh fruits or green vegetables should be eaten to supply the requisite vitamins. The diet should also include carbohydrates and salts. A condition of semi-starvation, with the food intake reduced to two-thirds its normal value, apparently can be endured for a period of several months without danger to health, but gives rise to a greatly reduced resistance to tuberculosis if extended over a period of several years. J.S.H.