Amateur Photographer & Cinematographer (1935)

The AMATEUR PHOTOGRAPHER P 6 CIMEMATOOrAPHER O ‘Deciders' Questions 'V ANSWERED General. — All communications for the Editor should be addressed : “ The Editor, The Amateur Photographer ana Cinematographer , Dorset House, Stamford Street, London, S.E.i.” and in every case, without exception, must *>ive the name and address of the writer. Contributions. — The Editor is glad to consider original, up-to-date manuscripts on photographic subjects. All contributions must be typewritten, or in very legible handwriting on one side of the paper only. Letters or communications arising out of matters already appearing in the paper are not paid for. The Editor disclaims legal responsibility for the safety of matter submitted to him, but he will endeavour to return rejected manuscripts, etc., when a stamped addressed envelope is enclosed. MSS. or prints that are not actually accompanied by a stamped wrapper or envelope can in no case be returned. Reproduction fees for prints are only paid by arrange¬ ment beforehan 1. The sending of a print, without any condition stated, will be taken as permission to reproduce it without fee. Enquiries and Criticism. — Advice, Criticism and Information are freely given, but the following conditions should be read careru'.ly before applying, as any communication which does not comply with the rules must be ignored. (i) bee General ' above. (2/ Every question and every print for criticism must be sent separately through the post, and must be accompanied by a separate stamped addressed envelope. No exception can be made in any case to this rule, except so tar as enquiries or prints from Overseas are concerned. (3) Neither enquiries nor prints for criticism must be enclosed with competition prints. (4) On the back of each print sent for criticism, in addition to the name and address of the sender, must be the title (if any), and the criticism coupon from the current issue. 15) Enquiries should be clearly written, on one side of the paper only, and should be specific and not general. Such enquiries as " How can 1 take interiors ? ” or *' Can you give me some hints on outdoor portraiture ? ” are too general to be dealt with in this section. (6) All envelopes should be distinctly marked “ Query ” or “ Criticism,” as the case may be. (7) Prints are sent for advice or criticism on the distinct understanding that by so doing per¬ mission is given for their reproduction without fee. We endeavour to deal promptly with enquiries, but cannot undertake to answer by return of post, npr can we give precedence to any enquiry. A selection or those replies is printed each week, but all questions are answered by post. Enquiries from abroad must contain a coupon also, but it need not be from the current number, and should be cut from the latest issue to reach the enquirer. Diazo Process. Where can I get a handbook dealing7with all the technical details of the Diazo process ? B. J. R. (New Southgate.) We have no knowledge of any text¬ book on the process you name. It is dealt with, however, in the “ Dictionary of Photography ” (obtainable from our publishers, price 8s. post free), where the information given occupies over two pages of letterpress. Brown Spots. Can you suggest the cause of the brown spots on the accompanying enlargement ? F. S. (Streatham.) The brown spots on your print are due to minute particles -of dry amidol settling on the wet print. You should never weigh out amidol in a room where prints are to be dried, or this sort of thing is almost bound to result. Shadows with Flashlight. In taking groups by flashlight I get awkward shadows falling on the row of people behind. How can I avoid this ? S. G. T. (Ilford.) The only way of avoiding unpleasant shadows falling on the back rows of a group is to burn the flaShpowder from a higher position. This throws the shadows of the people downwards, so that there is less chance of any faces at the back being obscured. If you can raise the level of the back row all the better. Beginners’ Competition. In the Beginners’ Competition is it necessary to have printed and developed the photos oneself ? P. M. S. (Cambridge.) The rules for our Beginners’ Competi¬ tion are published in the last issue of each month, and if you will refer to them you will find that both developing and printing by professionals are per¬ mitted, although either or both processes may be done by the competitor. Position of Diffuser. In using an enlarger should the ground-glass diffuser be between the light and the lens, or between the lens and the negative ? H. E. (London.) Neither of the positions you suggest is the correct one. The diffuser should be between the light and the negative, or between the light and the condenser, if the latter is in use. Making Developer. Are metol and amidol suitable for developing films and gaslight paper ? Is it necessary to add other properties to make up a developer ? W. C. (Luton.) Neither metol nor amidol alone forms a developer ; they are only single ingredients. When you want to develop films or papers you should use one of the developers given in the instructions with the particular film or paper you use, and make it up accordingly. Adon Lens. I have an old Adon lens ; can you tell me how to use it ? G. C. C. (Aberdeen.) We should advise you to write to Messrs. J. H. Dallmeyer, Ltd., of 31, Mortimer Street, Oxford Street, London, W.i, quoting the number of your Adon lens, and asking whether they can send you the book of instructions, which will give you all the necessary information for its use. Value of Stops. I have an old Kodak camera with stops marked 4, 8, 16, 32, 64 and 128. Are these f/ numbers ? The shutter has three speeds which are unmarked. \yhat are they likely to be ? A. M. (Tavistock.) Your lens is marked with what is known as the Universal System of stops, and the corresponding f/ numbers are 8, 11, 16, 22, 32, 45. The instantaneous speeds of the shutter are probably somewhere about i/25th, i/4oth and 1 /60th, but these suggestions must not be taken as anything like accurate. April 10th, 1935 Acetone. I have a developer formula containing acetone. Is the acetone a solution of celluloid in amyl-acetate ? How should the formula be prepared ? K. E. D. (Bristol.) We should advise you to buy the ordinary commercial acetone, although your assumption as to its composition is practically correct. If you wish to try this particular developer we should recommend it in the following form : Pyro, 1 oz. ; sodium sulphite, 4 oz. ; water, 9 oz. For use take 40 minims of stock pyro and 40 minims of acetone to every ounce of water. If you require to use bromide you should add a suitable quantity from a 10 per cent solution. Focussing Mounts. I notice that several cameras have lenses in focussing mounts. Are these mounts capable of long use without becoming inaccurate, or are bellows more satisfactory ? C. N. G. (Wanganui.) We have ourselves used focussing mounts over long periods without any sign of their becoming the worse for wear or inaccurate. Address of Makers. Would you give me the address of the HoughtonButcher Co., the makers of the Cameo cameras ? A. E. B. (Taunton.) The firm of Houghton-Butcher, the makers of the Cameo Cameras, is now known as Messrs. Ensign, Ltd., 88-89, High Holborn, London, W.C.i. Shutter Trouble. I send one or two prints, showing the same .trouble — an over exposed strip along one edge. Do you think this is due to the shutter ? If so, why does it not happen every time ? F. L. (Crewe.) Although you say nothing about it, we feel safe in assuming that you are using a focal-plane shutter, as the trouble is by no means an unfamiliar one. If you watch the shutter itself you will find that it slows down before it has completed its journey. It may even stop. This shows that the shutter has become sluggish, and requires over¬ hauling and perhaps a new spring. The trouble occurs at the slow speeds only, and increased spring-tension overcomes it ; hence the fact that the defect is not always apparent. Bisulphite Lye. Can I prepare bisulphite lye myself for using as a preservative for a stock pyro solution ? M. L. C. (London.) Dissolve 1 oz. sodium sulphite (good quality crystals), or \ oz. of the anhy¬ drous form, in 4 oz. of water, Add slowly, and with constant stirring, 85 minims of sulphuric acid. One ounce of this solution will act as an efficient pre¬ servative for 1 oz. pyro in a solution with a total volume of 9J oz. Covering Dishes. How should a dish be covered to protect plates from light during development ? Is something of the sort absolutely necessary ? J. J. (Leeds.) If not absolutely necessary, covering the dish is certainly advisable. Much depends on the light, and the distance from it. A sheet of millboard or strawboard will answer, but it gets stained with solution. A piece of thin vulcanite is better, as it can be kept clean. 50 342