Motion Picture Herald (Sep-Oct 1934)

September 2 2 , 19 3 4 MOTION PICTURE HERALD 35 11 I1, TEC UNO LOGICAL imiiiii The BLUEBOOK School By F. H. RICHARDSON A KINDLY CRITICISM John J. J. Dal, Austin, Texas, says: "Dear Brother Richardson : As this is my first letter in a long, long while, I dislike to start it with a criticism. In Bluebook School Question 232 you ask: 'In electrical formula, what do the letters E, C and R represent ?' "It is your use of the letter C that I arise to protest. In the Bluebook you use the letter C to represent current, whereas in recognized electrical formula that letter represents capacitance and the letter I current. True, a few years back the projectionist might never have learned the meaning of the word capacitance, and as a result been in nowise handicapped by the use of the letter C to represent current. Today, however, it is different and it is with the thought that your use of the letter C to represent current may tend to confuse the newer students of projection, that I offer protest and ask that you change your practice in that respect. Remember that users of the Bluebooks also read other handbooks and trade journals. "Brother Richardson, I am a senior electrical engineering student in a great college, the name of which I prefer that you omit should you publish this letter. I desire to congratulate you upon the manner in which you have conducted the Bluebook School. Many of the questions seem very elementary to me, but I must admit some of them make me dig out my text books and read up before I feel able to answer them. "To those who may be skeptical of the school, I want to say this : You have to this date not asked one question that at some time or other I have not had to answer in my University work. Furthermore, many things gleaned from your columns have come in mighty handy in that work. "Before closing I want to recommend a few books. First, the Bluebook, and that goes for every one. For those well advanced, having high school training and perhaps a year or two of college work, I would commend 'Radio Engineering Handbook,' by Henney, published by McGraw-Hill, price about six dollars. I consider this as the best radio handbook extant. "Second, 'Light and Sound,' by Duncan and Starling, published by the Macmillan Co., of London. Price about three dollars. "Third, 'Electrical Laboratory Studies,' by Upson. McGraw-Hill, two dollars. "Fourth, 'Six-Place Tables,' McGrawHill. Two dollars. It saves much time in making calculations. "Warning: These books are highly technical, making frequent use of complicated higher mathematical equations, especially calculus. Nevertheless, I believe the beginner, if he be really interested, will get enough out of them to justify their purchase. "I shall try to find time to write more frequently in future. I wish to thank you honestly and sincerely for the help you have been to me in the past and to assure you I look forward to a continuance of that same. In closing, I remain a student and admirer of Mr. F. H. Richardson." I might remark that Dal is not the real name of this friend. He has adopted a nom de plume, as have many others, first to avoid seeming to seek publicity, and second for the reason that those who do not wish themselves to do anything helpful sometimes try to make it unpleasant for others who do. In the older days very many have said: "I'm with you, F. H., but can't write any more as the other men here sneer and make nasty remarks." Later this has been gotten around by doing as Dal has done, first telling me, in confidence, their real name and address and adopting a nom de plume. "Dal" is a working projectionist. As to the letter I, its use in question 232 was an error. I have discarded its use in the forthcoming sixth edition of the Bluebook and will correct the error in the answers to the question. Several who answered that question I find also offered the same objection, in which both they and yourself were quite right. The use of C for current seemed to simplify matters a bit in the days when projectionists were little more than machine operators ; when many of them knew next door to nothing about electrical action, even often having heated arguments as to whether rheostats reduced volts or amperes. Capacitance— well, the term is a new one. Things are, as Dal says, different now and I is unquestionably the correct letter to use. Apologies ! Dal answers question 232 and I hope will find time to send in answers regularly. It is such men as he who, by their excellent answers to questions, make it possible for me to keep the school at a level where it has, as Dal says, very real value. V FLATNESS OF FIELD With regard to answer to section C of Bluebook School question No. 222, we have the following from an optical man of large ability : "Dear Mr. Richardson : With reference to your letter regarding test for flatness of field, it is quite true that in discussing certain matters with you recently I made reference to the fact that what is termed 'flatness of field' is sometimes ignored in the discussion of motion picture projection optics, and that much of the lack of sharp definition around the edges of the screen image is chargeable to that error. "It is well to stress the fact that flatness of field may be tested in very simple fashion, as set forth in your answer to section C, of question No. 222 in the Bluebook School. One only needs to have a large flat white cardboard, or other white paper that can be kept flat, and to hold it against the outer margin of the screen where things are fuzzy, though sharp at the screen's center, moving it slowly toward the projector. Cases will be found where the movement will be four or five feet before the image on the paper will begin to take on some semblance of sharpness. There will be cases where it must be moved even much further before the point of perfect sharpness is arrived at. "I am of the opinion that errors in field flatness are present in some degree in every projection lens. However, the test suggested will demonstrate the great difference in the work of high-grade projection lenses and those of inferior quality." May I suggest that here is an interesting experiment any projectionist can make, and it should be made. I believe, however, as per my answer to the Bluebook School question, one man should manipulate the cardboard and another view it from several feet of distance. The cardboard must of course be held flat with the screen surface for best results. Would appreciate reports from those who try this out. Textile Strike Hurts Theatres Theatre business in the textile centers, notably Massachusetts and Rhode Island in New England, and North and South Carolina and Georgia in the south, has felt the impress of the drastic mill strike, with all theatres closed indefinitely in certain localities and heavily curtailed box office receipts resulting in numerous others. Reports indicate attendance decreases amounting to from 10 to 50 per cent in affected areas. In Woonsocket, R. I., authorities last week closed all theatres for an indefinite period, as an emergency measure to prevent public gatherings, thus hoping to forestall rioting. Similar action was taken in certain situations in Georgia and South Carolina. Curtailed spending on the part of striking workers, in addition to general public caution which has caused numerous people to remain indoors after dark in the strike areas, has contributed materially to the attendance reductions which in some instances reached 50 per cent off normal. In the Atlanta area smaller cities have suffered, with many theatres operating only one or two davs each week.