Amateur Photographer & Cinematographer (1935)

October 2nd, 1935 The AMATEUR PHOTOGRAPHER p 6 CINEMATOGRAPHER g ‘Deciders' Questions yV ANSWERED General. — All communications for the Editor should be addressed : “ The Editor, Th? Amateur Photographer ana 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 rule* must oe 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 tar 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 cnticism, in addition 10 the name and address of the sender, must be the title (if any), and the criticism coupon trom 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 1 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 cannoc 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 trom the current number, and should be cut trom the latest k>sue to reach the enquirer Spotting Glazed Prints. Can you tell me an efficient method of spotting glossy prints for Press reproduction ? K. A. VV. (Saltdean.) The best thing to do in spotting glossy prints is to use a water-colour pigment to which a little gum has been added. Chromium Intensification. What is the cause of the orange colour in the enclosed film ? It has been intensified by the chromium method. R. D. F. (Watford.) The bichromate in the chromium intensification process stains the print heavily, and this stain must be removed by prolonged soaking and washing before redevelopment is started. The image itself remains a yellow colour, but, of course, turns black in the de¬ veloper, and there should then be no trace of yellow in the negative at all. Colour Filters. When using a colour filter must one use a tripod in order that the necessarily increased exposures be given without cameia shake. When is a colour filter advisable for landscapes, etc. ? B. J. (Catford.) With good subjects and an open light it is quite possible to give hand exposures with a light colour filter on the lens. This may be so light that it does no more than merely double the exposure. You will not obtain any noticeable advantage with such a filter unless there are blues in the sky or elsewhere, which would probably come out too light in the print unless a filter were used. Elon. What is Elon and where can I get it to make up a developing formula? F. S. K. (Loudon.) Elon is the name given by Kodak, Ltd. to their brand of taetol, and is supplied by them at any of their branches. Thus, whenever metol appears in a formula, it can be substituted, if necessary, by the same quantity of Elon. Convertible Lenses. What is the difference between a symmetrical and an unsvmmetrical lens. D. M. C. (Clapham Common.) These two terms are usually given to lenses of the “ Convertible ” or “ Combinable ” type, of which the front or back component can be used alone for the purpose of producing a larger image on the negative than would be obtained by using the lens complete. When this type of lens is called symmetrical it means that both the front and back components have the same focal length. When the focal lengths of these two components are not the same then the complete lens is said to be unsymmetrical. Focussing Scale. Can one work out a focussing scale for a camera by mathematics for a lens whose focal length is known ? D. M. B. (Finsbury.) Yes, it can be done by mathematics, but we would suggest that as the groundglass focussing screen must first be used for finding the infinity mark, it is quicker and more simple to continue by focussing by the ground glass on different distances and marking the corresponding measurements on the scale. Factorial System. What is meant by the “ factorial ” system of developing plates and bromide papers ? J. D. (Southend.) Briefly, it means that if the time taken for the first trace of an image to show after the developer is applied, is multiplied by the “ factorial ” number of the developer used, the product will be the total time necessary for the plate or paper to be completely developed. Different developers have different factors and in “ The Dictionary of Photo¬ graphy ” it will be seen that it can be as low as 4^ with hydroquinone, or as high as 40 with Rodinal. Enlargements. What is meant by “ lineal ” and “ diameters ” as enlargement terms ? C. D. F. (Glasgow.) The term " lineal ” means the length along a simple straight line, so that if a print were said to be six times “ lineal ” enlargement it would mean that the distance between two given points on the enlargement would be exactly six times larger than the distance between the same two points on the negative. The term " diameters,” which is more commonly used, means the same thing. If we divide the diagonal of the negative portion to be enlarged into the diagonal of the enlargement, the quotient will be the number of diameters enlargement. This number of diameters enlargement is sometimes expressed as 6 x , or 6 magnifications. This is opposed to the term of " area ” enlargement, which should never be used as an indication of the degree of enlargement. Lens Hoods. Which is the better type of lens hood, a complete tube or one which has one side partly cut away ? D. O. (Swansea.) Where the light is coming from one source and there are no reflections from other directions then, perhaps, the “ cut away” hood is better than the complete tube. But when there are strong lights coming from all sources then a complete tube is better, but it must be lined in¬ side with some non-reflective material, such as black velvet. Borax and M.Q. Developer. Can you supply me with a formula using M.Q. with Borax for fine-grain development? M. C. (Sheffield.) A suitable M.Q. and Borax formula is as follows : Metol • • 4 grs. Hydroquinone . . 10 grs. Sodium sulphite (anhy.) •• i oz. Borax ■ ■ 4 grs. Hot water . . • • 5 oz. Pinholes in Bellows. How can I fill up pinholes in mv bellows ? T. T. (Rochdale.) Mix a little rubber solution, such as is sold for repairing cycle tyres, with some powdered lamp-black. If this is worked into the inside of the fabric or leather when the bellows are fully extended, and allowed to dry, it will prove an effective remedy. When the pinholes are very large, then an additional support is required in the form of small pieces of black court plaster, particularly when the hole is in a corner of the bellows. Enlargers. What advantage has a condenser enlarger over the condenserless pattern ? J. D. (Dover.) With the illumination and lens aperture being equal in both patterns, the condenser enlarger is considerably faster, and tends to give a slightly stronger tone contrast in the print. On the other hand, it reveals all blemishes and retouching, as the condenser gives directional lighting, unlike the other pattern which gives diffused lighting, i.e., “ scattered ” light which softens down all blemishes. 30 344