, UNUSED CAMERAS
By W. B. AYLING STATISTItS show that there are between four and five million, individual users of photographic apparatus in Great Britain.; Of this number, not more than two hundred thousand take photographs all the year round. Thus a great deal of the pleasure to be derived from photography is lost to the majority of amateurs, for I do not include the profes- sional photographer in this statement.
It is a ;remarkable fact that whereas a golfer will play, regularly 'each week-end, year in and year out, the photo- grapher in so many cases ceases to take any interest in his; camera between the months of October and March. Consider' the most likely reasons for this state of affairs. In years gone; by, or up till six years ago, the apparatus and materials available were unsuited for photography on dull days, except with the aid of cumbersome tripods and time exposures.
All this is now changed, and with the modern type of camera there is seldom a day, no matter how dull, when a photo- graph could not be taken with the camera held in the hand. In addition, small devices are available with which the camera. can be clipped to a piece of furniture, railings, motor- car, or to any convenient and rigid object, and with which exposures of one second or longer may be used without fear of shaking the camera and so spoiling the picture.
; Films have advanced in speed some six times -during the last five years, and the lens equipment has been speeded up from four to six times. Consequently one-thirty-sixth of the exposure previously needed can now be given with reasonable, chances orsuccess. I think I should be safe in asserting that Out of six amateurs, four would be perfectly content if out of a roll of film of eight pictures, four were good and the remainder not so good. Why should this be so ? There is nothing very difficult in securing six or seven out of eight, all perfectly good from the user's point of view.
In. the desire to assist readers who may expiiien-ce-Inine of these Troubles, it has been proposed that I should enumerate the most prevalent causes of trouble and endeavour to show how these may be overcome by the ordinary, user of the camera, that is the amateur who practises photography for pleasure. There are some faults, sufficiently uncommon to be encountered by the few, and I will gladly deal with these if written to, care of the Editor of The Spectator. Enquiries should not be sent about ordinary routine troubles. They will be dealt with in due course in later articles.
The most common fault in everyday or " genre " photo= graphy is that of exposure. There is, of course, a correct exposure. There is also a latitude of twice this in either direction. If the correct exposure for any given film, at a given aperture (the size of the opening of the lens in relation to the distance from lens to film surface) should be 1-20th of a second, then an exposure of 1-4oth, or of z -loth, will yield a good picture, practically indistinguishable from that of the ideal exposure. It is, however, not an easy matter to decide what should be the ideal exposure without some kind of instru- ment for measurement of the light value. It is generally agreed that the photographic value of the light is that reflected from the object being photographed, and not the value of the light falling upon it. It can well be imagined that the light reflected from the side of a building in full sunshine might be one hundred times more powerful than the light reflected from the shaded side of the same building at the same time. Only a person with constant and lengthy experience could be expected to estimate correctly the light values in such widely divergent cases.
The occasional user of a camera can get very good guidance from the use of an exposure meter, ranging in price from 6s. for the cheapest to E5 or so for the most useful type. In the former case the meter takes the form of a gadget with a window partially obscured, through which the scene is viewed, and a scale or table attached converts what is seen into expo- sure and aperture. The combination of time of exppsute and aperture provides the necessary information to it:Cure th& best result. The more expensive apparatus usually cOiisistx of a photo-electric cell coupled to a scale. The instrument is pointed at the object to be photographed and the position of an indicator. noted. Again, a table or scale converts the actual reading into the exposure and aperture needed. Once the user is conver- sant with these meters, it is very easy to use them. All film material is not of the same kind. Some is more sensitive to certain colours than others, some is slow in action and some fast. On every packet of film is an indication of the speed and characteristics of the material. The same applies to plates, although their names are fast disappearing from the amateur's vocabulary.
In films of German origin, the speed is given in DIN, meaning Deutsche Industrie Normen, and indicating a system of speed calibration -for photographic-emulsions, and it may be that the outer carton containing the film is printed 7/10 DIN. Another system is known as the Scheiner, and ia this case the measurement would be given as SCH 170. The older system, and one still employed by one of the largest British manufacturers, is known as H & D, and the measure- ment would be indicated by the figures H & D 250. These are not comparative figures. Each of the three systems differs so much that any attempt to reconcile one with another has met with partial failure because there is little in common between them. They are all attempts to classify film emul- sions.according to the rcaction of that emulsion to light, and this is as far as comparison can go. All this seems to compli- cate the job of the poor fellow with the camera, but in actual practice it is not nearly as bad as it sounds. The main points to-Consider when taking a-photograph, at least as far as exposure is concerned, are : (a) The speed of the film.
(b) The actual value of the light.
(c) The speed of the shutter.
(d) The size of aperture.
The first two factors will determine the latter two, or a,b and c can determine d, or a, b and d can determine_ c. (a) The speed of film is usually given on the packet, item (b) is pro- vided by experience, tables or an exposure meter -(c) and (d) are definitely related to one another, and may vary one with the other in a predetermined way. On the lens mount of all but the very cheapest cameras some numbers will be found; which indicate the aperture. In most cases -these are in a definite state of progression. If they are marked with " f / "- preceding the number, for instance f/5.6 the next number (increasing) may safely be taken to indicate double the exposure. '14.5 needs, let us imagine, i /6oth of-a second, f15.6 will need i /3oth, ancl_f /8 /i5th. These are not strictly correct, but will serve without complicating the matter unnecessarily.
The true state of progression is f/2 (a very fast aperture), f/3.5, f/5, f/7, f /to, f/14. -Each of these sizes of opening, or apertures passes only half the amount of light passed by the f /number" preceding it, and requires twice the length of exposure'. If ilk -Correct expOsure is 3 seconds at f /7, then the same- effect could be secured by 12 seconds at f/5, and so On. Again these statements refer only to exposure; • other considerations sometimes determine the aperture and duration of exposure. A rough and ready guide to exposures can be obtained from photographic diaries, the Burroughs Wellcome Diary containing a simple calculator affixed to its inside cover. Clear instructions upon the method of using meters are always enclosed with the instrument, and can be followed easily.
In my next article I hope to deal with everyday faults, their . causes and cure, and to provide hints which I hope will make the anigeur photographer's work of more interest to him.
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