Amateur Photographer & Cinematographer (1935)

Thi AMATEUR PHOTOGRAPHER I ■a 6 CINEMATOGRAPHER o | December 18th, 1935 ‘Qeaders Questions A. 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 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 bv return of post, nor can we give precedence to any enquiry. A '.election of those replies is printed each week, but all questions are answered by post. Enquiries from abroad rmi't contain a coupon also, but it need not be from the current number, and should be cut from the latest issue to reach the enquirer. Pictorial Composition. Can you furnish me with the name of a book that deals with the art side of photography like the series of " Picture Points ” that appears every week in “The A.P.”? J. H. MacR. (Lancashire.) We know of no book that deals with the subject of composition, etc., in anything like the same way as it is being treated week by week in our pages. There are certain books which deal mainly with the art side of photo¬ graphy, but we hesitate to recommend one in preference to all the others. We think your best plan will be to write to Messrs. Sands Hunter & Co., Ltd., of 37, Bedford Street, Strand, London, W.C.2, and the Fountain Press, of 19, Cursitor Street, London, E.C.4, for their catalogues, in which you will find a list of all current books classified according to subject. Sky Filters. Can you explain the functioning and effect of a graduated sky filter when used in front of the lens ? YV. VV. (London.) The question you raise cannot be dealt with adequately in the form of a reply, although it has at times been explained at considerable length in our pages. We may say, briefly, however, that the effect of a sky filter depends mainly upon its distance from the lens. If it is close to the lens it may function exactly the same as a uniform filter, but as it is moved farther from the lens its action becomes more selective. Reduction on Sepia-toned Prints. Is there any method of local reduction that I can use on a sulphide-toned print, similar to the Farmer’s reducer used on ordinary black-andwhite prints ? C. M. (London.) We think you are likely to cause trouble with a sulphide -toned print if you use any method of local reduction. What we would suggest is that you make the necessary modifications on the print before toning, instead of attempting it afterwards'. Bolting Silk for Diffusion. I have been quite unable to obtain bolting silk in my neighbourhood as fine as the two samples enclosed. Can you kindly tell me who can supply it ? G. B. (Norfolk.) We have obtained bolting silk for diffusion purposes from such firms as Messrs. Ensign, Ltd., 88-89, High Holborn, London, W.C.i ; Messrs. Kodak Ltd., Kingsway, London, W.C.2, and Messrs. Jonathan Fallowfield, Ltd., 6162, Newman Street, Oxford Street, London, W.i, but we doubt whether, in any case, the mesh is the same as that of either of the samples you send. If, however, you will apply to these firms they will tell you what is available. Steel Developing Tanks. Is there any objection to plain steel being used for a developing and fixing tank ? It would, of course, be kept free from rust and scales. R. YV. (YVolverhampton.) A steel tank that is not covered with anti-acid enamel would certainly be affected by some of the solutions, and is therefore not considered desirable. Probably the best tanks are of monel metal (a patent, stainless metal), but the majority of tanks are brass and heavily nickel-plated. Diffusion in Enlarging. I have tried to get a soft definition on my enlarge¬ ments by projecting through muslin held between lens and paper, but although I keep the muslin moving and have given exposures for as long as fifteen minutes, I cannot get the desired effect. Can you suggest the reason ? L. S. (London.) Your exposures seem unusually long, and you cannot expect to keep anything moving for so long a time. If you stretch either a single or a double thickness of black chiffon over the front of the lens you will probably get all the diffusion you want. Bolting silk can also be used. Chiffon permits shorter exposures than muslin. Full aperture of the lens should be used. Hypo-Alum Toning. As my attempts at hypo-alum toning have given me only purple tones, can you give me an alterna¬ tive formula ? K. R. (Persia.) The formula you have got will be difficult to improve on, and if it is properly used the colour of the print will depend upon the time for which you continue toning. Process Blocks. Can you advise me on a suitable handbook on the block-making process, as I wish to illustrate a book from photographs ? H. M. (Bishop’s Stortford.) The making of half-tone process blocks is a highly technical business requiring considerable experience and expensive plant and materials. It is a matter not lightly to be attempted by the amateur unless he intends to take it up seriously. A firm that specialises in books and materials for reproduction processes is Messrs. Hunter-Penrose, Ltd., of 109, Farringdon Road, London, E.C.i. Emulsion Speed Equivalents. Can you supply me with a conversion table for emulsion speeds for the various systems? Re¬ garding chloro-bromide printing, I have difficulty in obtaining sufficient contrast, although I use an M.Q. bromide developer. Can you suggest any reason ? T. G. (YVorcester.) The whole subject of plate and film speeds is in a state of confusion, and the number to which you refer is prob¬ ably the Continental H. & D., which is entirely different from our own. Ilford, Ltd., issue a useful table of comparative speeds that may help you. We do not know why you have difficulty in getting sufficient contrast on chlorobromide paper from negatives that work well with normal bromide. Judging from the rest of your letter, you may be over¬ exposing and under-developing. Further, you will not get the right results with chloro-bromide papers by using an M.Q. developer suitable for bromide, which is altogether unsuitable. This is probably why you have to resort to toning. Enlarging. I am buying a quarter-plate enlarger to use with two sizes of negatives, quarter-plate and Ensign Midget size. Can you tell me if it will be quite suitable for the smaller negative and what size enlargement it will give me? It will enlarge from j-plate to 12 x 10 in. S. L. (N. London.) You can easily use the small negative as well as the quarter-plate one. The degree of enlargement can best be found by trial, although the calculation is quite simple. If you can enlarge from quarter-plate to 12x10 in., this is enlarging three diameters, so that the biggest enlargement you can get with the smaller negative will be three times its length and breadth. Half-watt Lighting. YY'hat exactly is meant by the term of “halfwatt" lighting? E. M. R. (YValthamstow.) The earlier type of electric lamps gave one candle-power of illumination per watt, the unit of electrical consumption, but with the introduction of gas-filled electric lamps this ratio has been in¬ creased to one candle-power per half¬ watt of consumption. Hence the term of “ half-watt ” lighting. 603 24