How to add sound to amateur films (1954)

light-weight pick-up using a sapphire stylus is more convenient. It will play hundreds of records before it requires attention, and it is just as kind to them. So much for non-sync; that is to say records chosen and played to fit the film fairly well. When you want records made to fit your film, problems appear. It is not a simple matter to make your own recordings on discs. However well the equipment is designed, it still requires very careful manipulation. One mistake ruins a disc costing several shillings. Fortunately, commercial recording facilities are available and at a reasonable price. These services make it unnecessary for you to have recording equipment of your own. You can leave the manipulation of the recorder to a skilled technician and concentrate on producing the commentary or effects you require. The result will be a set of high-quality recordings which you can play on your twin turntables (see also p. 51). Many years of research have brought the quality of disc recording and reproduction to a very high standard. Notes and overtones containing as many as 8,000 vibrations or cycles a second are commonly recorded. Some of the latest recordings extend to 14,000 cycles. This is beyond the limit of hearing of many middle-aged and elderly people and far beyond the capabilities of even the best radio set on the medium waveband. Frequency response is not everything, however. There are inherent difficulties in reproducing mechanically these very high frequencies. Other methods of recording and reproduction have therefore been developed which do not use a vibrating needle. Optical Recordings Professional cinema films carry sound recorded photographically alongside the picture. This arrangement has several advantages over the use of a separate disc. The photographic sound record is printed in the same operation 42