Amateur Photographer & Cinematographer (1933)

December 27th, 1933 Thi amateur photographer p 6 CINEMATOGRAPHER o Rl eaders 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.t ” 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 net 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. 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 post, 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 ucr 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 snould be clearly written, on one side of the paper only, and should be specinc 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 witn in this section. (6) All envelopes should be distinctly marked “ Querv ’’ 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 canno: undertake to answer by return cf 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. Enquir.es from abroad must contain a coupon also, but it need not be from the current number, and should be cut lrom tue latest issue to reach the enquirer. Shutter Speeds. What is the use of such slow speeds as one second and half a second on the shutter of a hand camera if it is not safe to give more than i/25th of a second ? C. B. (Croydon.) You Evidently mean that a longer exposure is unsafe with the camera held in the hand. This is often the case, although many hand-camera users can give much longer exposures than i/25th of a second without camera movement. Everyone can give the longer exposures when the. camera is used on a tripod, or otherwise supported or steadied. Stereoscopic Prints. Can you state briefly the correct way of trimming and mounting stereoscopic prints ? C. N. L. (Taunton.) Standard size prints should be trimmed to a width of about 2I in., and mounted 1 /8th of aninch apart. The inner side of each print should show i/8th of an inch more of the subject than appears on the outer side of the other print. Pneumatic Release. I have a shutter with a rubber tube which always perishes sooner or later. Is there anything that can be done to keep the rubber soft and elastic ? F. P. (Chelmsford). It has been recommended that oc¬ casionally the release is immersed for an hour in ammonia one part, water two parts. Probably the best course is to have a wire (antinous) release fitted instead. This will last indefinitely. Keeping Hypo. As it is more economical to buy hypo in fairly large quantities will you tell me if the crystals will keep well ? J. L. A. (Eastbourne.) The crystals must be kept dry, that is all. Our own practice is to store hypo in one of the large stoneware jars used for jams and pickles. The bung should be sound and kept well pressed down in the mouth of the jar. Rust on Negatives. Through using an old metal dish 1 have got rust stains on some negatives, one of which I send. Can this rust be removed ? F. L. (Preston.) You might try washing the negatives in 10 oz. of water containing 50 grs. of oxalic acid. This acid is very poisonous, but can safely be used for this purpose. Gelatine Coating. How can I coat unsired papers with gelatine so as to make them suitable for Transferotype prints ? P. U. L. (Exeter.) Soak one ounce of white gelatine in water till it has swollen as much as possible. To the gelatine add about 20 oz. of water, stand the vessel con¬ taining it in a saucepan of water, and raise the temperature till the gelatine Completely melts and can be stirred up into a thin solution. Apply this warm to the paper with a soft hog-hair brush, keeping the coating thin and even. For some papers two or more coatings may be necessary, allowing one coat to dry completely before applying the next. The gelatine solution must be kept standing in hot water during use, or it will set. Masking Enlargements. What is the best method of getting cleanly marked edges on a bromide enlargement ? 13. H. (Oxted.) A simple but effective method is to expose the paper behind a sheet of clean, flawless glass to which a paper mask of appropriate size has been attached. Several masks of the kind on separate pieces of glass are an advantage. Numbering Films. How can 1 put numbers on film negatives for indexing purposes without disfiguring the picture ? W. B. (Tenby.) As good a way as any is to write the number on the clear margin of the nega¬ tive with a fine pen and fixed indian ink. 600 Retouching. I can only get a very little lead on the negative when I try' retouching with a pencil. Are special pencils required ? H. S. M. (London.) Any good lead pencil is suitable. What you must do first is to rub smoothly on to the negative a trace of retouching medium, a small bottle of which you can obtain through a photographic dealer. Very little lead is applied in any case. Stop Bath. What is meant by a “ stop ” bath when making gaslight prints ? What is the object of using it ? W. N. (Peterborough.) It is a solution which at once arrests any further developing action, and a further purpose is that it neutralises the alkalis of the developer so that they do not impair the fixing solution. A simple formula for a stop bath is an ounce of acetic acid in 20 oz. of water. Per Cent Solution. I require to make up a solution of hypo to a strength of 6 per cent ; what is the correct pro¬ cedure ? B. C. (Glasgow.) Weigh out 6 oz. of hypo and dissolve it in, say, a pint of hot water. Make up the total volume to 5 pints. This will give you 100 oz. of solution containing 6 oz. of hypo. The quantities may be more or less than those given, but the proportions must be the same. Copying. I wish to copy some entries in slightly faded inkon parchment that is rather yellow. What plate should 1 use ? What filter ? What light ? What exposure ? J. G. C. (London.) We should advise you to use a slow orthochromatic plate with a yellow filter. This will brighten up the render¬ ing of the parchment, and if you do not get sufficient contrast it would help matters if you intensify the negative. If you can arrange to use diffused day¬ light we think that would be preferable, unless you can get a very steady artificial light. In any case, whether you use daylight or some form of artificial light, you must find the exposure by actual experiment, as the factors entering into the matter are too numerous and uncertain for us to offer even an approxi¬ mate suggestion. Work with Enlarger. Is it possible to use a J-plate enlarger for 3X4 cm. negatives ? What definition would I get ? Would you recommend a condenser or diffuser type ? Would an enlarger adapted to fit a camera give satisfactory results ? S. R. S. (Birmingham.) There is no reason why you should not use a quarter-plate enlarger for smaller negatives. The definition does not depend upon the size of the enlarger at all, but on the original negative, the quality of the lens in the enlarger, and your ability to focus correctly. You can get good results from these small negatives either with a condenser or by diffused light ; it is largely a matter of choice. The definition should be satisfactory in either case. There are many efficient enlargers which take the actual camera as part of the apparatus, and here again there is no reason why the results should not be as good as with any other type of enlarger. 26