Amateur Photographer & Cinematographer (1936)

April ist, 1936 The AMATEUR PHOTOGRAPHER o 6 CINEMATOGRAPHER o ‘Deciders Questions A, ANSWERED General. — All communications for the Editor should be addressed : “The Editor, The Amateur Photographer nnd 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 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 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 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. 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 irom abroad must contain a coupon also, but it need not be from the current number, and should be cut trom the latest issue to reach the enquirer. Steaming Prints. What is the purpose of steaming bromide prints after retouching and how is it done ? M. O. B. (Taunton.) The purpose of steaming the emulsion side of bromide prints is to help to make the retouching less apparent as well as imparting a slight sheen to the surface that brightens up the picture and enriches the shadows. After retouching, and before trimming and mounting, the emulsion side of the print is held very close to a jet of steam and quickly passed over it in a regular motion so that the entire surface of the print has been steam-heated. This softens the emulsion and so tends to absorb any retouching on the surface, and when dry again partially fixes the retouching. You are advised to experiment on a spare print first, as it requires a little skill to manip¬ ulate it correctly. Negatives for Enlarging. I am told that a “thin” negative is best for enlarg¬ ing purposes. Is this correct, and does this mean that the negative should be under-exposed or under-developed, or both ? L. B. (Brighton.) As enlarging tends to increase the tone contrast from a negative, particularly with big enlargements and with con¬ denser enlargers, it is generally advisable to produce a negative that shows less tone contrast, usually called a " thin ” negative. But this does not mean that the negative must be under-exposed in order to be “ thin.” In fact, it can be slightly over-exposed with advantage and the development time shortened by 10 to 25 per cent according to the tone contrast in the subject and exposure given, or, with normal exposure, the developer used can be of the “ soft ” variety, such as Azol, Rytol, Rodinal, Certinal, etc. This should produce a “thin” negative, one full of detail, but possessing neither dense blacks nor transparent film. A " thin ” negative must not be confused with a “ flat ” negative, which is the other extreme, and which is generally caused by over¬ exposure and/or under-development. Pumice for Retouching Prints. What is the exact procedure and pup)ose of using pumice powder for preparing bromide prints for retouching purposes ? L. A. S. (Hampstead.) In order to give a suitable surface or " tooth ” to the print, so that powder colours, such as conte, etc., can be applied easily and worked into varying gradations, a small quantity of pumice powder is dusted on to the surface and lightly rubbed in with the ball of the finger for a minute or so. The surface is dusted clean and should then be ready for retouching. For shading purposes the shading stump is very use¬ ful and enables large areas of even tones to be introduced. All surfaces of bromides can be treated with pumice with the one exception of glossy prints. Focussing Point. I want to photograph a large group where the nearest person is about io ft. away and the farthest person is about 30 ft. away. On what distance should I focus the lens ? The lens is 6-in. focus and f/4.5 aperture. G. T. (Chester.) To obtain the correct focussing point the following formula is used. Multiply the two distances together and multiply the product by two. Divide this by the sum of the two distances added together, and the quotient will be the focussing distance for the lens. In your case the equation is as follows : 10x30x2 600 = =i5 ft. 104-30 40 If the camera is focussed on this point, the depth of focus table should be consulted as to the largest possible stop to use, in order that every person in the group shall be sharply defined. Exposure Meter Preference. Can you recommend me an exposure meter that is practical and efficient ? A. D. (Southend.) It is entirely against our practice to recommend one article in preference to another of a similar kind, and we only express opinions in the form of reviews in our pages. Speaking generally, we may say that we know of no exposure meter which has all the virtues and none of the faults of such instruments, and all the well-known makes have their advocates and users. Copyright. If by winning a prize in a snapshot competition which stipulates that the copyright of the negative is automatically surrendered to the newspaper concerned, does it mean I must never make another print from that negative, even though it has not been asked for ? F. M. (Lincoln.) Yes. Strictly speaking, the newspaper which holds the copyright of the nega¬ tive need not ask for possession of the negative itself, and it is understood that while the negative remains your pro¬ perty, you cannot make another print or reproduction, even for home decora¬ tion, let alone sell it to other people. To do this would be an infringement of copyright and the newspaper could claim, on proving it, either their own fee or damages. Self-capping Focal-plane Shutter. Will you please explain the meaning of the term “ self-capping ’’ as well as “ focal-plane ” and “ roller-blind ” shutters ? C. S. (Southampton.) A focal-plane shutter is one which operates immediately in front of the focal plane of the lens and this focal plane coincides with the plate and ground glass. But because nearly all focal-plane shutters in fabric form are rolled up and dropped similar to a window roller blind, a " roller-blind ” shutter is not necessarily a focal-plane shutter, and is more usually a shutter that fits in front of the lens, and one that was very popular twenty years ago. In order to make the exposure, the focal-plane shutter must possess an aperture or slit, and this slit can take the form of being variable or fixed. It is obvious that if the plate were uncovered and the lens open and there was nothing in between, such as a reflex mirror, the negative would be exposed to the light as the blind was being wound up pre¬ vious to the intentional exposure. To overcome this a device is fitted which covers up the slit as the blind is being wound up, but allows the blind to drop with the slit open. This is known as a self-capping focal-plane shutter. Enlarging Papers. Why is it that P.O.P., self-toning and gaslight papers are not advised for enlarging purposes ? L. J. (Epping.) When it is explained that gaslight papers can be two or three hundred times as slow as bromide papers, it can be understood that they are much too slow for exposing purposes to artificial light through a lens. As for the printingout papers mentioned, it would take, literally, weeks to get an image under those conditions. They are intended for exposing to daylight, and for contact prints and not enlargements. 58 310