Amateur Photographer & Cinematographer (1936)

January ist, 1936 The AMATEUR PHOTOGRAPHER n 6 CINEMATOGRAPHER a ‘Deciders Questions 1 V ANSWERED General.— All communications for the Editor should be addressed : “The Editor, The Amateur Photo crabber and Cinematographer Dorset House, Stamford Street, London, S.E.i,” and in every case, without exception must give the name and address of the writer. 1 ' COMTRIBUT'ONS.— The Editor is glad to consider original, up-to-date manuscripts on photographic subiects. All contnbutions must be typewritten, or in very legible handwriting on one side of the paper onlv Letters or communications aris.ng 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 beforehand. The sending of a print, without any condition stated, will be taken as permission to reproduce it without fee. Enquires ant. Criticism.— Advice, Criticism and Information are freely given, but the following conditions ignored °e read Carefu y before aPP'ym as any communication which does not comply with the rules must be (i) See “ General ” above. (2) Every question and every print for criticism must be sent separately through the post and must he accompanied by a separate stamped addressed envelope. No exception can be made in any case to this rule, except so far 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 (5) 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 doin-* per¬ mission is given tor their reproduction without fee. We endeavour to deal promptly with enquiries but cannot undertake to answer by return of post, nor can we give precedence to any enquiry. A selection of 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. Exhibiting Cine Films. Are there any regulations or restrictions to observe if I show my 16-mm. cine films to a paying audience ? Should 4 also be subject to entertain¬ ment tax ? F. W. (Barking.) If you propose to show inflammable cine filrris we would strongly advise you to apply to the local police to ascertain the restrictions imposed, and you will probably find it out of the question to be able to comply with them. You will certainly have to pay enter¬ tainment tax on all tickets which are above the free scale. Reducer. Can you give me the formula for the potassium cyanide-iodine reducer referred to in a recent article called “ The Genesis of an Exhibition Picture ” ? G. B. (Cheshire.) There are various formulae for the reducer you name, but you must re¬ member that this solution is very poisonous. You must prepare two stock solutions. A. — Dissolve 150 grs. of potassium iodide in a little water, and add 45 grs. of iodine flakes. When all is dissolved make up the bulk to 20 fluid ounces. B. — 10 per cent solution of potassium cyanide. A suitable formula is : A, 150 minims ; B, 100 minims, in 20 oz. of water. Developer Strengtheners. I should appreciate some information on the use of strengtheners enabling tank developer to be used repeatedly. I use a roll-film tank. I. B. (Surrey.) The reinforcement of a developer is only used in the case of very large tanks which are in constant use day after day. The method cannot be applied to de¬ velopment in an ordinary daylight tank, where, naturally, the solution should only be used once, or the time and temperature table will not work. Measuring Solids. Can I use a graduated measure for making up formuhe or must I use scales ? A. D. (Glamorgan.) You cannot rely upon graduated measures for arriving at accurate quan¬ tities of solids; they must be weighed out in the usual manner. This is especially important when making up small quan¬ tities. Dual Purpose Focussing Scale. I have just bought a camera which has its focus¬ sing scale adjustable for about 3/i6ths in. If I move it forward a letter “ F ” is revealed, and a letter “ P ” is shown when the scale is brought back. What is the meaning of it ? N. F. (Birmingham.) Your focussing scale has been made a ljustable according to whether plates or films are being used. It is presumably one of those cameras which will take either roll films or plates in slides. The letter “ F ” refers to " films ’’ and should always be seen when films are being used, but when plates are being used the scale should be brought back to reveal the letter “ P.” Curvature of Field. Can you tell me what is wrong with my anastigmat lens ? Focussed on all distances it is either sharp in the centre of the ground glass, or, if I move the lens slightly forward, sharp again only on the edges of the focal plane. H. C. (London.) A good anastigmat should have a practically flat field, but yours seems to present slight curvature. The differ¬ ence in definition is probably only visible at large apertures, but if, as we suspect, the field of the lens is slightly curved, no position of the lens will give you good central and marginal definition at the same time. Assuming that the lens components are all in their correct position, and that none of them is loose, your only remedy is to employ a small stop, when it is necessary to have sharp focus all over the negative. Amidol Developer for Gaslight Paper. If an amidol developer is suitable for gaslight printing paper, could you give me a working formula ? C. M. (Skegness.) You will generally find an amidol developer recommended with every make of gaslight paper. Here, however, is a formula, but it must be made up fresh just before use : Sodium sulphite . . . . 480 grs. Potassium bromide . . 4 grs. Water to . . 20 oz. Then add dry amidol . . 50 grs. Black Tones on Bromide Papers. Can you tell me how I can get the same rich blacks on bromide paper as can be obtained on gaslight paper ? My proprietary developer usually gives me only brownish blacks. R. C. (London.) There is no reason why you should not get as good blacks on bromide paper as on gaslight. If with your developer you get a brownish tone, you are prob¬ ably over-exposing and consequently under-developing. Either M.Q. or ami¬ dol will give good blacks on any bromide paper if properly used. Dead-black Finish on Metal. Can you tell me how I can restore the enamelled parts of my camera and slides to their original matt-black finish ? A. H. (Coventry.) You will find it difficult, if not im¬ possible, to get the same finish on metal as was produced originally. Any photo¬ graphic dealer will get you a dead-black for the purpose, and with most of these you will find information as to thinning down with turpentine or something of the sort if necessary. Anhydrous Sulphite. How is anhydrous sulphite better than crystals ? How should the quantity be adjusted if crystals are used instead ? G. E. S. (Colwyn.) The advantages of anhydrous sulphite are that it keeps better, and is more quickly dissolved. There is no reason, however, why you should not use the crystals, and in that case you should always take double the weight given for the anhydrous form. Use of Photograph. 1 took the enclosed photograph some time ago, and now want to sell copies on calendars. Must I get permission from the residents whose houses are included, or is the copyright mine without asking ? Need I consult the local Council ? A. VV. (Westerham.) As you took the photograph yourself the copyright is yours, and you can do anything you please with it without consulting anybody whatever. We are speaking of this particular photograph, and not laying down general principles. Composition. Can you tell me of any books which deal with composition, etc., as in the articles on " Picture Points ” ? J. H. H. MacR. (St. Helens.) We know of no book available which deals with the subject of composition and so on in the same way as do our weekly articles. Information on composition occurs in many books, more or less in¬ cidentally, but we can truthfully say that we know of no better means of obtaining guidance than by the weekly study of our pages. There is no issue of the paper in which composition, lighting and such matters are not discussed. 26 24'