Amateur Photographer & Cinematographer (1933)

August 2nd, 1933 The AMATEUR PHOTOGRAPHER ta 6 CINEMATOGRAPHER a ‘Deciders' Questions ANSWERED General. — All communication^ for the Editor should be addressed : " The Editor, The Amateur Photographer cud Cinematographer. Dorset House, Stamford Street, London. S.E.i,” and in every case, without exception, must give the name and address of the writer. Contributions. — The Editor is glad to consider oricrin.il. 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 beforehand. The sending of a print, without any condition stated, will be taken as permission to reproduce it without fee. Fnquiries and Criticism. — Advice, Criticism and Information are freely given, but the following conditions should be read carefully before applying, as any communication which does not comply with the rules must be ignored. (1 ) See " General " above. (2) Every question and every print for criticism must be sent separately through the T ost, and must be 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. Sucn enquiries as “ How can I 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. W e 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 u eek, 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 is-m • tcreach theenauirer Stained Dishes. I have badly stained several white porcelain dishes (domestic) with chemicals, and the stains will not wash off. Can they be removed by any other means ? T. M. (London.) We cannot say definitely. The fol¬ lowing treatment has been suggested. To a tablespoon of hydrogen peroxide add an equal quantity of water, and then half a teaspoon of liquid ammonia. Mix well, and apply to the stains with a soft rag. Rinse, and then wash in a pint of warm water in which half an ounce of borax has been dissolved. Even if this treatment answers perfectly you will probably conclude that it will be better in future to use dishes which may be stained with impunity. Fixing-hardening Bath. How much alum should I add to acid-hypo solu¬ tion to make it act as a hardener as well as a fixer ? E. M. (Dudley.) You must proceed in a different man¬ ner from that suggested. Dissolve i lb. hypo in 40 oz. hot water, and let it cool. In 10 oz. of water dissolve i£ oz. potas¬ sium metabisulphite, and 180 grs. chrome alum. Add the second solution to the first, and make up to 80 oz. by adding water. Recovering Fogged Plates. 1 accidentally opened a packet of plates in daylight. Can you tell me whether they can be saved for any purpose, or are they hopelessly fogged and must be thrown away ? F. A. (Portsmouth.) Plates or films which have been accidentally fogged by exposure to light may be recovered by immersing in the following solution : Chromic acid, 30 grs., potassium bromide 60 grs., water to 10 oz. Allow tfye plates to soak in this bath for five minutes in the dark-room, then wash and dry. The plates can then be used, but are very slow, and will need from five to ten times the normal exposure. Glass for Glazing Prints. What is the best method of preparing plate glass for glazing prints ? N. S. (Sheffield.) There are many methods used accord¬ ing to the choice of the worker. In the first place, wash the glass thoroughly with water to which a little hydrochloric acid has been added. A gentle stream of water from the tap should flow evenly over the glass without any sign of “ greasiness.” Polish the glass. Dab over the surface with a pad of cotton¬ wool containing a little French chalk. Polish again. If the glass is kept well wrapped up when not in use, the washing will be required only at intervals. Intermediate Rinsing. Is it absolutely necessary to rinse negatives between development and fixing ? E. P. (Cambridge.) Opinions differ. Some object on the score that the developing action con¬ tinues, possibly unevenly, during the rinsing. Others contend that rapid rins¬ ing does no harm, and minimises con¬ tamination of the fixing bath. If the fixing bath is acid, as it generally is nowadays, no harm of any kind seems to result from transferring the negative direct from developer to fixer. In such a case, however, it is advisable to renew the fixing solution rather more often than otherwise. Hydroquinone Developer. Can you oblige me with a hydroquinone (not M.Q.) developer ? I want one that wilt give plenty of contrast and density. L. J. (Bury.) You will find that the following meets your requirements : A. Hydroquinone . . . . 160 grs. Sodium sulphite . . .. 2 oz. Citric acid . . . . 60 grs. Potassium bromide . . 40 grs. Water to . . . . . . 20 oz. B. Caustic soda . . . . 160 grs. Water to . . . . . . 20 ozs. A suitable working solution is A, 1 oz. ; B, 1 oz. ; water, 2 oz. Spots on Negative. Can you explain the cause of the spots on the enclosed negative ? B. A.T. (Caterham.) Judging from the size and character of the spots we should say that before development the plate was splashed with hypo solution, which dissolved out the silver and so left nothing to be developed. No doubt you can judge for yourself whether it was possible lor this to happen. Anyhow, we cannot suggest any other probable cause, especially as you do not say when the clear spots were first apparent. Modified Print. I send a reproduction, cut from a newspaper, of a tennis player. How was it taken to make the player stand out so brilliantly while everything else is subdued ? J. E. (Tottenham.) It was not taken like that at all ; the print has been modified. Grey colour has been sprayed over the whole of the subject except the figure and the fore¬ ground, which were either covered with a mask during the spraying or cleaned up afterwards. The result is really entirely false in tones, but this sort of thing is often done for the sake of emphasis. Grain in Print. Can you tell me if the grain on the surface of the enclosed print has been obtained with bolting silk ? S. H. A. (YVhitby.) It has not. What you rather in¬ appropriately call “ grain ” is a par¬ ticular texture given to the surface of the paper in making it. Such papers are obtainable under the description of linen, canvas or rayon surface. Bolting silk actually breaks up the image, which in the example you send is unbroken. Large Stop. I have just obtained a camera with a lens working at f/2.9. How does an exposure at this aperture compare with that at f/8 ? H. C. J. (Margate.) The rule for these and all other stops is to square the f/ numbers and compare the results. Thus 2.9x2. 9=8. 4, and 8x8 = 64. So that the exposure for f/8 is about 7} times that for f/2.9. Iu practice you would give, as nearly as you could manage, only one-eighth of the f/8 exposure when using the larger stop. Damaged Films. I laid some films out on a sheet of blotting-paper to dry, and they stuck to the paper. I have pulled them off, but cannot use them as they are. What do you suggest ? H. C. (Toronto.) In the first place we suggest that in future you pin your films up by one corner to the edge of a shelf and let them dry with both surfaces freely exposed to the air. You do not seem to realise that the back of a film is coated with plain gelatine to counteract the pull of the gelatine on the sensitive side, and so prevent curling. You can probably save your negatives. Soak them well in clean water. Lay each one face down¬ wards on the bottom of a dish of water, and rub oft the soft paper with a plug of cotton-wool. Remember all the time that wet gelatine is easily scratched and otherwise damaged. 30 120