Amateur Photographer & Cinematographer (1933)

Im AMATEUR PHOTOGRAPHER ] a 6 CINEMATOGRAPHER a I August 16th, 1933 ‘Deciders' Questions ANSWERED General. — All communications for the Editor should be addressed : “The Editor, The Amateur Photographer 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. 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 f tamped 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. Enquiries 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 Tost, and must be accompanied by a separate stamped addressed envelope. No exception can be made in any cass lo 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 ine 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 lee. 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 ot 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 issu^ tc reach the enouirer. Architectural Work. I l.ave used a quarter-plate camera with a focus¬ sing screen, but find it rather complicated. X want a camera ready for use, without so many gadgets, capable of taking landscapes and archi¬ tectural subjects, which I photograph most. Would the — — or the camera be suitable ? Can you suggest a camera ? W. L. (Birmingham.) It is quite impossible for us even to attempt to advise you on the questions you put. Architectural subjects, for example, cannot be adequately dealt with with a camera always ready for use. Neither of the cameras you name could be recommended for architectural work, as they have practically none of the movements and adjustments so often necessary. If you cannot manage a camera with a focussing screen we do not see how you can seriously attempt architectural work at all. Price of Print. What would be a fair average price to ask for a print for publishing as a calendar ? L. H. (London.) There is no such thing as a fair average price for prints for reproduction. You must enter into negotiations with the purchaser and get the best price you can. Poor Prints. Why are the enclosed prints so fogged and in¬ distinct ? What would be the remedy ? What alternative arrangement of exposures, etc. should have been adopted for the negatives ? M. M. (Honor Oak.) We cannot give you any useful advice regarding the prints you send. These are very poor in quality, but we cannot tell to what extent this is due to the prints or to the negatives. We do not think there was much wrong with the exposures of the negatives, but even with a correct exposure it is quite possible to go very far wrong afterwards with the negatives, or the prints, or both. If you repeat your question and send negatives instead of prints we may be able to help you. Stained Print. What is the cause of the stain on the enclosed bromide print ? J. R. (Shelly.) It is not possible to say definitely the cause of the stain on your print, but we should say that the most likely cause is that, while in the fixing bath, part of the print rose above the surface and was exposed to air. This is a print that must always be watched. Margins on Negatives. I have been told that it is possible to treat film negatives so that they will give a black or white margin on the print, whether by contact or enlargement. If this is true, how can it be done ? W. B. (Ilford.) To get a white margin, rule lines close to the four sides of the negative, and paint outside the lines for a sufficient distance. Use opaque ink or pigment. Any part of the negative, instead of the whole, can be masked in this way. For a dark margin, trim the film so as to leave only the actual subject required. If the film is laid on plain glass, the whole surround of the picture will be dark. In both cases the margins ob¬ tained must be trimmed true afterwards, and should generally be very narrow. Value of Stop. If I use a quarter-plate lens on a 3J X 2$ plate, how can I find the altered value of the stops ? , M. E. (Torquay.) j The value of the stop is not affected. The expression " a quarter-plate lens ” does not mean anything definite. As your lens covers a quarter-plate it will naturally more than cover a 3 J X 2 \ plate, but its focal length remains the same, and the stops retain their marked values. Pyro-Metol. Is it possible to combine pvro and metol for nega¬ tive development ? F. H. (Forest Gate.) Certainly. An “ Imperial ” formula is : A. Metol . . . . 45 grs. Potassiummetabisulphite 120 grs. Pyro . 55 grs Potassium bromide . . 20 grs. Water to. . . . . . 20 oz. B. Sodium carbonate ... 4 oz. Water to. . . . . . 20 oz. Prepare as follows : Dissolve metol in 12 oz. of water, and metabisulphite in 4 oz. ; mix ; add pyro, then bromide, and make up to 20 oz. For use, take equal volumes of A and B. Rapidity of Lenses. I have a 4pin. lens working at f/6.3, and a friend of mine uses a 6-in. lens, also working at f/6.3. I claim that my lens must be faster than his because it works nearer to the plate. Am I right ? S. H. (Edmonton.) You are wrong. The lenses are of the same speed. As the focal lengths are different the diameters of the apertures are different in proportion. The stop in your friend’s lens is certainly farther from the plate than yours, but at the same time it is larger. The more powerful light passing through his lens exactly makes up for the greater distance it has to travel. Dextrine Paste. Can you briefly repeat the method of preparing a mountant from dextrine ? E. B. A. (Exeter.) Add half a pound of white dextrine by degrees to cold water to make a smooth cream. Then add half a pint of water, and boil in an enamelled saucepan till clear. Kept in covered jars or bottles it soon sets into a white paste. Unless the paste is to be used in a short time a preservative must be added. Before adding further water to the cream, stir in a dram of oil of cloves, or almonds. Deposit on Negatives. However long I wash my film negatives they are dirty and smeary when dry. I enclose an average sample. Where do I go wrong ? F. F. (Fratton.) You are not necessarily going wrong at all. In some districts, and even in different parts of the same district, the character of the water causes the trouble. We have frequently suggested that before the films are hung up to dry, both sides should be swabbed with a plug of cotton wool, laying the film on the bottom of a dish of water for the purpose. Another good plan is to wash the films in acidified water — say, half a dram of hydrochloric acid to five ounces of water — and then give a final rinse or two in clean water. Angle of View. How can I find the angle included by a given lens ? L. K. (Quebec.) Presumably you should have added, " on a given plate.” On a piece of paper rule a line equal to the diagonal of the plate. Bisect this line, and erect a perpendicular equal to the focal length of the lens. Join the end of this line to the ends of the first line. This forms a triangle, and the angle at the apex is the angle of view included. 166 32