Amateur Photographer & Cinematographer (1937)

The AMATEUR PHOTOGRAPHER ^ 6 CINEMATOGRAPHER o June 2nd, 1937 ‘Deciders Questions /V ANSWERED General. — All ccmmunications 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, mus' 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 be will endeavour to return reiected 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 tee. Enquiries and Criticism. — Advice, Criticism and Information are freely given, but the following condition^ 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 bv 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 lor 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 from abroad must contain a coupon also, but it need not be from the current number, and should be cut from the latest issue 0 reach the enquirer. Focal-plane Speeds. I have recently bought an old Ememann focalplahe camera, but find that the shutter is not marked in actual speeds in fractions of a second. The width of the slit can be varied from o to 4 (centimetres ?) and the tension can be varied from o to 12. Where can I find what speeds the various possible combinations of slit and tensions represent ? H. W. K. (Essex.) Cameras of the type to which you refer almost always had a metal plate affixed giving the principal speeds of the shutter ; it would appear that the plate that your camera once possessed has been lost at some stage of its career. We can only suggest that you take your camera to a large London dealer and see if he can find out for you what the speeds are by comparing your camera with another one on which the speeds are marked. Condenser versus Ground Glass. I am making an enlarger for 3} x 2} negatives, and find that with a piece of opal glass half an inch from the bulb I get even illumination. Would the addition of one condenser lens between opal glass and negative increase the efficiency ? And which arrangement — single condenser, double condenser, ground glass, or opal glass — would give the best results with regard to definition ? W. F. (Perth.) Adding the condenser lens should make the picture more brilliant, es¬ pecially if its presence allows you to dispense with the opal glass, relying on an opal bulb for sufficient diffusion. Definition depends solely on the sharp¬ ness of the negative and on the ability of the lens used to project this negative with absolute sharpness ; condensers, ground-glass and the rest only control the evenness and brilliance of the illu¬ mination, and make no difference at all to the definition obtained. Grey Enlargements. When I make contact prints on gaslight paper I get excellent results, but in enlargements the whites turn grey, the greyness increasing with the degree of enlargement. I enclose a negative or two for your inspection, as well as some of the enlargements. A. H. W. (Old Trafford.) To begin with, there is nothing wrong with your negatives, which are capable of producing perfect enlargements. What is the source of the trouble with your enlargements we cannot say for certain, but your procedure must be seriously at fault somewhere. It would appear that, somehow or other, actinic light reaches the whole surface of the paper, probably during exposure. We can only suggest that you watch your proceedings throughout, and see if at any stage actinic light falls on the paper other than that forming the image during exposure. And you must include as at least “ possibly actinic ” the light from your dark-room lamp, for even orange light, if there is enough of it, will fog bromide paper. Pyro-Metol Developer. Can you give me a good formula for a pyro-metol developer, preferably one that will keep for some time ? J. D. (Sheemess.) The following is a pyro-metol formula : A. Pyro . . . . 40 grs. Metol . 35 grs. Potassium metabisul¬ phite . . . . . . 90 grs. Potassium bromide . . 15 grs. Water to . . . . 10 oz. B. Sodium carbonate . . 660 grs. Water to . . 10 oz. Dissolve the metabisulphite, then the pyro, and then the metol in solution A. For ordinary development take A one part, B one part, water one part. So long as solution A is not seriously discoloured, you may safely assume it to be in good working order. If you make it up with boiled water, and store it in small bottles filled to the neck and securely corked, it should last some months. Solution B will keep almost indefinitely. Some Development Queries. I have just purchased a tank and would be glad to have a suitable M.Q. formula, with times for ortho, and pan. films, that I could use with it. Is it better to use a fairly strong developer for a short time, or a weak developer for a longer time ? Should I use plain or acid hypo in the tank ? B. J. W. (Carlton.) There are many metol-hydroquinone formulae, but we should advise you to select one recommended by the makers of the sensitive material you use. It is impossible to give any definite times for development, as these vary, not only according to the character and strength of the developer, but according to the make of sensitive material and also according to the character of the negatives you require But if you use, as suggested, the formula given by the makers of your film, we should expect that they would also give some idea at least of development time. There is a limit to which the developer can be safely diluted for tank work, for you must always be sure that the solution contains sufficient of the active elements to do the work required A very dilute solution might fail in this respect. We do not recommend the use of an acid-hypo bath in a tank which has any metal parts ; a plain hypo bath is less likely to do damage, but the greatest care must be exercised in subsequent cleansing. Restoring Faded P.O.P. Prints. In a recent issue advice was given for restoring a faded bromide print. Can you tell me how to restore a faded P.O.P. print (or it might be selftoning) that I have in my possession ? G. W. (Oldham.) We do not know of any safe and reliable method of restoring a print made on any form of P.O.P., which is not nearly so reliable in its response to after-processes as bromide paper. Since any chemical treatment is more than likely to ruin the print beyond redemp¬ tion, we think your best plan will be to make a new negative by copying on a slow ordinary plate. A Matter of Copyright. A private person, A, goes to a professiona photographer, B, in the ordinary way to have his portrait taken. A buys a dozen or so prints, but finding the charges high has one of the prints copied for making further reproductions. I think A is within his legal rights in so doing. Am I correct ? J. F. L. (Liverpool.) In the case you state we agree with your opinion. B owns the actual negative, but is not entitled to make prints from it without the order or consent of A. The copyright in the prints belongs to A, who is quite entitled to ma*ke new negatives for producing further prints. Copying. Can you advise me as to type of camera to purchase for copying same size ? And am I right in thinking f/6 is the best stop for the purpose ? FI. V. T. (Romford.) The main essentials of the camera for the purpose you name is that it must have an extension sufficient to bring the lens to twice its focal length from the plate. We do not know why you should fix upon f/6 as the best stop for copying. The stop to use is the largest that will give satisfactory definition. 56 591