Amateur Photographer & Cinematographer (1937)

May 12th, 1937 The AMATEUR PHOTOGRAPHER n & CINEMATOGRAPHER a 'D eaders Questions 'V 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 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 to reach the enauirer. Cleaning Dishes. I have been given some xylonite and porcelain dishes which are old and terribly badly stained. Can you suggest how I could clean them ? G. G. (Nottingham.) We should advise you to get a little commercial hydrochloric acid, sold as spirits of salts,” and you might dilute it with an equal volume of water. Pour some of this in the dishes and let it stand for some time ; then pour off and clean out the dishes with plenty of water and a brush. Do not get the acid on your hands or clothes. The xylonite dishes will probably be safe for use, but if the porcelain dish has been used for hypo, this will probably have pene¬ trated into the dish and may give rise to trouble. Delayed Action. I often see a shutter described as “ D.A." which, I believe, stands for “ delayed action." What does this mean, please ? K. A. K. (Derby.) A delayed-action shutter can be set for any exposure and the trigger released. The actual exposure, however, does not take place until after a lapse of a certain period — 15 or more seconds. The point of this is to enable you to take up your position to be photographed, alone or with others, before the shutter goes off. Anastigmat or Not ? I have just bought a second-hand camera with an f/6.3 lens. I was told this was an anastigmat, but there is no mention of this stamped either onthelens or on the camera. How can I confirm that the lens really is an anastigmat ? G. A. W. (London). By no means all anastigmat lenses are so marked ; it is much more usual to engrave on the mount the trade name of the lens. We have never known any indication of the sort you have been looking for to be stamped on the camera itself. But it is practically a certainty that the lens you have comes into the category of anastigmats, since aplanat lenses of apertures over f/8 have not been made for some years. Strong Rendering of Clouds. I am anxious to get a strong rendering of white clouds against blue sky without loss of detail or tonal values in the foreground. Can you suggest any means of improving on the enclosed, taken on pan. plates through an Ilford Delta filter ? H. M. L. (Edinburgh.) We do not think you can expect any better results than those you send. If you use a filter that will make the blue sky darker you will probably be in difficulty about the rendering of the rest of the subject, which even with the filter you have used shows some slight signs of over-correction. But if you do not mind an over-corrected foreground, or in cases where it has no very definite colours — e.g., grey stone buildings, etc. — you could strengthen your clouds still further by using a red filter. Another suggestion is the use of a polarising screen (Zeiss Herotar) which will darken blue sky without affecting colour-rendering of foreground objects. This, combined with a Gamma or Delta filter, might do just what you require. M.Q. versus Pyro. Can a well-balanced M.Q. developer be modified to make the most of under or over-exposed negatives as is done with pyro-soda ? 1 ask this because I already use M.Q. for paper and have very little space for storing solutions. A. W. N. (Walsall.) Such control in development as is possible — and it is not as much as is sometimes believed — can be secured with an M.Q. developer as well as with pyro-soda. In any case, however, it is necessary to note beforehand when there is a case of serious over or under-expo¬ sure, and modify the developer accord¬ ingly. For example, for under-exposure with M.Q. you could increase the metol and decrease the hydroquinone, while for over-exposure you would do the reverse and add bromide. Naturally, such methods as these are only suitqd to roll films when all negatives are equally wrongly exposed. Watkins Time Thermometer. I recently picked up a Watkins Time Thermometer at a sale, but find it is graduated in minutes in¬ stead of degrees. How do I use it, please ? F. D. (Rochdale.) The whole method is fully described in the “ Watkins Manual of Photo¬ graphy,” where it occupies several pages. In brief, it consists in adjusting the dilution of the developer to suit the particular plate or film to be developed, and then making allowance for tempera¬ ture by giving the development-time indicated by the thermometer you have. Like all time-and-temperature systems, the figures are only correct for the developer for which they were worked out ; the “ Watkins Manual ” gives a choice of formulae. Lantern Slides from Thin Negatives. I have a good many negatives from which slides are required by enlargement. Some are on the thin side, and 1 should be glad to know of any maker who provides vigorous lantern plates fast enough for enlarging upon. H. H. B. (Wokingham.) Although the slowest lantern plates are not intended for enlarging methods, we think you might try them in the circumstance you name, and we would add the suggestion that you reduce exposure time by using a Photoflood bulb in your enlarger. Unless, however, the negatives are exceedingly thin, you ought to be able to get good results on warm-tone plates by cutting down exposures to a minimum and prolonging development accordingly. Photographing Reflections. 1 have been told that if a puddle is six feet away, and an object twelve feet beyond it is reflected in the puddle, the reflection is eighteen feet away. Is this so ? P. M. B. (Dorchester.) If you photograph the reflection of an object in a mirror, the distance to focus on is the sum of the distances from object to mirror and from mirror to lens. This is so because the light reflected from the object has to travel this distance before reaching the lens, just as if the object itself were that distance away and no mirror intervened. The fact that the light is deflected by the mirror on its way does not make any difference so long, of course, as the mirror is flat. Lens Quality and Prices. I am trying to decide between two cameras at much the same price. Both have lenses of the same aperture, by the same maker, but one lens is considerably more expensive than the other ; naturally, therefore, the camera with the cheaper lens has an extra refinement or two. What shall I lose by choosing the more attractive camera with the less expensive lens ? E. H. C. (London.) In all such cases as you mention you may quite safely take it that the more expensive type of lens is a better instru¬ ment, but it does not follow that the cheaper form will not do all you require in the way of ordinary photography. It is when it comes to critical tests that the better instrument shows its qualities, and if you do not demand the utmost detail, or the very highest degree of enlargement, you may in practice find the cheaper lens indistinguishable from the other. So much depends upon individual standards that the decision in such a case as yours has to be left to the prospective purchaser himself. 34 499