The rapidity of plates can be measured by an instrument called a sensitometer. That one in general use is made by Warnerke. But this sensitometer, like many so-called scientific things in photography, seems to us very unscientific, for the light cannot be uniform; for, as is well known, the light given from phosphorescent paint varies in intensity with the temperature. Since writing this, we have been informed that this has been proved to be the case by Dr. Vogel, who, in addition, brings against this sensitometer serious errors of experiment, due to yellow glass being employed. Dr. Nicol, too, has stated that the screens sent out vary in density.
|On exposure tables.|
We have seen how the rapidity of a lens is determined; beyond, then, the comparing the relative rapidities of lenses, all tables of exposures are fallacious and unscientific. Can absurdity go any further than some of the data of some of these so-called scientific tables: “Panoramic View,” “Living objects out of doors,” &c.? Briefly, what is the difference of exposure required on a living ass and on a dead donkey, both out of doors? But seriously, let the student be not led away by such chimeras, for there can be no tables of exposures until the science of meteorology is as fixed a science as mathematics; and any attempt to work by exposure tables will end in dismal failure. If our word is not sufficient to convince any reader, let him note what two eminent scientists think of these tables. Dr. Vogel says, in one of his works, “There is no rule which determines the length of time a photograph has to be exposed to the light;” and Captain Abney has told us he considers such tables absurd and unscientific. It is with his sanction that we quote him on the subject. Exposure must be judged by circumstances: no artificial aids will help. Fortunately for us, plates allow of considerable latitude of exposure.
But as in all good things, simplicity goes hand in hand with perfection. We have advocated quick exposures as absolutely essential to artistic work, and it follows, therefore, that in making quick exposures there is less liability of going wrong; so the two work hand in hand. He who exposes slowly misses the very essence of nature, and it is this very power of exposing so quickly that gives us a great advantage over all other arts. The painter has to resort to all sorts of devices to secure an effect, which perhaps only lasts for half an hour in the day. Not so with photographers, if we see and desire to perpetuate an effect, it is ours in the twinkling of an eye, and thus in a really first-rate photography there will always be a freshness and naturalism never attainable in any other art. And here we would state definitely that the impression of these quick exposures should be as seen by the eye, for nothing is more inartistic than some positions of a galloping horse, such as are never seen by the eye but yet exist in reality, and have been recorded by Mr. Muybridge. Here, then, comes in the artist, he knows what to record and what to pass over, while the craftsman, full of himself and his dexterity, tries to take a train going at sixty miles an hour, and lo! it is standing still, or he expends his energy in taking a yacht bowling along abeam because that result is more difficult to obtain than to take it going away from him, and he calls it natural and therefore artistic. Of course such performances are born of ignorance and vanity. Hundreds of such things have been done in the past, hundreds will be done in the future, and they will sell, but only to be finally destroyed. No photographer has yet done a series of marine pictures; here and there one sea-picture has been done which has oftener been the result of chance than of art. As for the ordinary photographs of yachts, they are mere statements of facts that merit no artistic consideration.
Here, then, we must leave the question of exposure. It is, perhaps, the most important and the most difficult of all photographic acts. In the studio the matter is simpler than out of doors, because the light is not so much affected by reflections and various meteorological conditions; in landscape work, on the other hand, exposure becomes a most difficult problem, yet long experience can bring an intelligent man to give comparatively correct exposures, so that the resulting picture may be developed to obtain the exact impression that he requires, still, even after years of experience, he will at times find himself baffled and humiliated by failure.
It is in exposures that intuition acts as it does in all intellectual matters, and he who can seize on the right exposure at once by instinct is the photographer born, and unless, after some practice, the student can do this, there is little hope that his work will ever rise above mediocrity.
CHAPTER VII.
DEVELOPMENT.
Study of chemistry.
Before entering on the subject of development, it is necessary to tell the student that if he does not already understand the principles of chemistry, he should lose no time in doing so, and as aids to such understanding he cannot do better than get Roscoe’s “Lessons in Elementary Chemistry,”[[12]] and Abney’s “Photography with Emulsions,” and master the chapters mentioned in the footnote, ignoring the rest for the time. Also let him buy Bloxham’s “Laboratory Teaching.” For a few shillings he can purchase apparatus enough to do qualitative analysis. This he will be able to do by following Mr. Bloxham’s directions, omitting, perhaps, testing with the blow-pipe. If he has the time and means, he will do well to do some quantitative analysis, working, say with water, since it is of such immense importance to the photographer. He will find a knowledge of chemistry as interesting as useful, and the power of observation and accuracy acquired by the study will be invaluable in subsequent stages of his work. We refer the student to works on chemistry by specialists, because we think it is a mistake to swell the bulk of our book by an exposition of chemical principles. We caution the student, however, who intends to take up photography as an art, to have nothing to do with plate-making. |Plate-making.| That manufacture can only be done satisfactorily by experts constantly employed at it, and it is as reasonable to expect a painter to prepare his own colours, and make his own canvas, as to insist upon a photographer making his own plates. Some people have tried to propagate the false idea that a picture taken on a plate of the exhibitor’s own making has a special kind of merit, but obviously this is only true when the object is an “Emulsion process competition.” In judging of the merits of a picture, no facts should be taken into consideration, save the art expressed by the picture. |Plates.| Still the student should know the methods by which his plates are prepared, and that his chemistry will teach him, and when he has found plates which suit him, let him keep to them. We have worked with fourteen different kinds of plates, and have found most of them good, though each requires different treatment. One piece of advice is, however, necessary, always buy your plates direct from the makers, unless you can rely upon your dealer. Some plates are, of course, much quicker than others, and this point the beginner must carefully bear in mind, making his exposures accordingly. |Vigilance committees.| He must not forget, however, that there are brands of plates which are “starved” of silver; these he should avoid, and it would be well if a vigilance committee were appointed in every society to test batches of plates occasionally, and report on them in the photographic journals, thus showing up the fraudulent manufacturers. Assuming, then, that the student has carefully studied the chemistry of development and has fixed on a satisfactory brand of plates, we will proceed to give him a few practical hints, but before we do so we must get rid of an obstacle in his path, and that is the wet-plate process.