Amateur Photographer & Cinematographer (1933)

November 8th, 1933 Ihi amateur photographer p 6 CINEMATOGRAPHER e ‘Deaders ’ 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 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, fa) 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 anv ca n to this rule, except so far as enquiries or prints from Overseas are concerned. (3) Neither enquiries ncr 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 iss..e. (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 I take interiors ? ” or “ Can you give me some hints on outdoor portraiture ? ” are too general to be dealt with in this section. (6) AU envelopes should be distinctly marked “ Query ” or “ Criticism,” as tne 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 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. 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 emuirer. Water Bath. A contributor refers to transferring a film to a water bath to reduce contrast. How long is the film immersed in this ? If the method is used for one negative on a roll film will it affect the other negatives on the roll ? P. J. C. W. (Whitstable.) You cannot adopt the method sug¬ gested when you are developing a whole roll of film. The procedure is to take the negative from the developer, when the high-lights appear, and transfer it for some minutes to a dish of plain water, covering the dish to keep out the light. The film is then returned for a few moments into the developer, and again transferred to the water. The effect has to be judged by observation, and no special times can be given. Reversed Film. The whole film from which the enclosed negative was taken is the same. Can you tell me what has gone wrong ? Is it possible to correct the result so as to get a print ? D. A. K. (Bexley Heath.) You cannot get an ordinary print from the film, which is now a positive instead of a negative. This is probably due to exposure, during development, to an unsafe light. Your only possible chance is to expose a slow ordinary plate under the film, so as to try to get a negative from which you can make prints. It will not be altogether satisfactory even if you succeed, as reversal is not entirely complete, although a little skilful re¬ touching of the negative would be sufficient to put it right. Sky Filter. I read in an article that a sky filter is useless, yet such filters are made and sold. What is your opinion ? P. E. W. (Deganwy.) A sky filter certainly answers the purpose for which it is made, but a great deal depends upon its position in front of the lens. The only real objection to such a filter is that exposure is cut down, not only for the sky, but for all objects rising up against it, and this is sometimes inconvenient. Heat in Enlarger. I am making an enlarger with the help of my own camera. Will enough heat be concentrated on the lens to damage or discolour it ? R. J. C. (Exeter.) You need not have any apprehension about the heat of your enlarger damaging the lens in any way. The exposures should not be sufficiently long to create any perceptible heat at the lens position. Copying. I have a reflex with a 5-in. lens, which I wish to use occasionally for copying ; would a supple¬ mentary lens enable me to do this ? H. M. S. (Glasgow.) We hesitate to recommend the method you suggest for copying, although it sometimes answers well enough. Pre¬ sumably you wish to copy same size, in which case, with your present lens, you must have at least io in. extension to the camera. It does not follow that a supplementary lens will suit the par¬ ticular lens vou are using, and there is no telling what effect it would have on the definition. Moreover, for about the price of a good supplementary lens, you could pick up second-hand a quarterplate field camera with long extension, which would do the work much more conveniently, and with which you could use your present lens as it is. Dark-room Clock. In a recent article a dark-room clock was illus trated ; can von tell me wher“ I can purchase one like it ? C. H. T. (Batley.) We cannot identify the particular make of clock from the illustration, but there are several such pieces of apparatus on the market. Messrs. Jonathan Fallowfield, Ltd., of 61-62, Newman Street, Oxford Street, London, W.i, list one with both seconds and minute hand, and an alarm which will ring at any time from half a minute upwards. This costs 25s. Messrs. Kodak sell a similar clock at ^2, and Messrs. Agfa, Ltd. (1-4, Law¬ 438 rence Street, London, W.C.2) have a clock which signals at 1 to 60 seconds, and sells at 18s. 6d. Cleaning Lens. While working by the sea the lens of ray camera has been stained by salt spray. How can I clean it safely ? F. H. (Manchester.) Perhaps the best way of cleaning your lens would be to use a very soft cloth, preferably not silk, slightly moistened with alcohol. You might, however, tr}' plain water first, as, if there is nothing but a slight deposit of salt, this treatment should remove it. Blocking Out. I have a negative of a group of people three of whom I wish to enlarge into separate portraits. How can I block out the rest of the negative without spoiling it ? R. E. S. (Merton Park.) We think that the best way to manage what you desire is by blocking out with " Photopake." You should first cut a mask which will block out everything except the head required and its im¬ mediate surroundings, and then paint round the head with Photopake until the blocking out and the mask together eliminate everything but the head. When you have dealt with this one you can wash the negative, dry it, and pro¬ ceed t» the second and third in a similar manner. Hypo-Alum Bath. I understand the procedure of toning bromides with hypo-alum, but shall be glad of a reliable formula for the bath. Can you oblige ? F. B. L. (Hove.) Dissolve the following in boiling water in the order named, adding the alum slowly while stirring. Hypo . . . . . . 5 oz. Lump sugar . . . . 1 oz. Alum (potash) . . . . 1 oz. Water . . . . 40 oz. Harden the prints in alum, place in the cold bath, and slowly raise the temperature. Yellow Stain. When I bleach negatives or prints with acid bichromate I find that long washing is necessary to remove the yellow stain. Can the process be expedited ? B. D. (Darwen.) Yes. Wash briefly in several changes of water ; apply a 5 per cent solution of potassium metabisulphite till the removable stain has gone ; wash again as before. Tank Pyro. Is there such a thing as a good single-solution pyro developer for tank use ? L. B. (Bradford.) Make up the following just before use : Sodium sulphite . . . . 60 grs. Sodium carbonate . . .. 40 grs. Pyro . . . . . . 10 grs. Water . . . . 10 oz. Stained Slides. Using a hydroquinone developer for lantern slides I find yellow stains on some of them ; is there a remedy ? T. G. C. (Halifax.) Do not unduly prolong development ; rinse well ; use an acid-hypo bath. To remove stains try : Thiocarbamide I OZ. Citric acid I oz. Water 20 OZ. 24