Naturalistic Photography for Students of the Art.

by P. H. Emerson

All other exposures might be called time exposures, it being understood by this term, that the exposures were long enough to be counted by the second-hand of an ordinary watch. A note could always be added giving the number of seconds the plate was exposed.

We are perfectly aware this method would give only approximately rough statements of the times of exposure, but that is all that is wanted for ordinary work, for after all, except in delicate scientific experiments, the times given to exposure must always vary greatly, for exposure, as we shall show, can never be reduced to a science. On the other hand, in cases of delicate scientific work, it may be required to measure exactly the length of the exposure, and this is easily done with the proper apparatus, as applied by Mr. Muybridge and others. Our nomenclature is intended for the use of ordinary operators, so that they may describe more accurately than they now do the exposure given to a particular plate; and it is at any rate more accurate than any nomenclature now in use, for, as we have shown, by the camera cloth method a quicker exposure can be made than with many shutters working slowly. The fundamental distinction, it seems to us, for everyday work is, whether the time of exposure is measurable by the seconds-hand of an ordinary watch or not, and that is the point on which our nomenclature is based. Hence, when we use the term “quick exposures” in this work, we mean it as already defined. |Name of shutters.| The shutters themselves should, we think, be called “quick exposure shutters,” or simply “exposure shutters,” instead of instantaneous shutters. We will say but few words on “shutters,” as these mechanical aids to exposure are called.

Exposure shutters.

Theoretically, the best shutter is that which allows the lens to work at full aperture for the longest time, and which causes no vibration or alteration of the position of the apparatus during exposure. The mechanism should be simple and strong, and the whole small in bulk. Mr. T. R. Dallmeyer’s new central shutter, in our opinion, best fulfils these requirements. Another important matter is the correct position of the shutter, and this, theoretically again, is behind the lens, providing the aperture be large enough to prevent any of the rays of light admitted by the lens being cut off. But in practice, a shutter working in the diaphragm slot of the lens answers best, and the very worst way of all is to work the shutter on the hood of the lens.

Quick exposures.

All portraits should be taken by shutter, and by quick exposure, if possible; in fact, we feel sure a first principle of all artistic work in photography is quick exposure. There is nothing to be said for time exposures, although we are fully aware how much has been written on their advantages, and the beneficial effects on the resulting negatives. We, however, have never seen these wonderful gains, and for quality we have seen very rapidly exposed plates result in negatives which will hold their own in quality against any, whilst in every other respect, there is everything to lose in “slow” or time exposures. There are cases, of course, when time exposures are admissible, and even necessary, as in certain grey-day landscapes, but when dealing with figures or portraits in good light, let the exposure be as quick as possible, ere the freshness and naturalness of the model be lost.

Variation of exposure.

From what has already been said, the student can understand that the exposure will vary with the attendant circumstances. When he considers that there are several factors to be considered in determining the length of exposure, such as the lens used, the diaphragm, the hour of day, the season of the year, the constantly varying conditions of light, the subject and the plate used,—he will see how hopeless it is to lay down any rule for the time of exposure, but it will be as well to consider the effects of these factors, and thus briefly to indicate to the student what he must especially study.

The lens and diaphragm.

We have already shown how the rapidity of different lenses may be compared. This factor, then, can be determined, but after all it is of little practical value. It is no doubt necessary when a new lens is used, and every photographer may, when using a lens for the first time, have to work out its ratio intensity, but as most workers know their lenses, this factor is hardly worth considering, for by practice the operator easily determines their intensities.