To the beginner in photographic work the use of other than an ordinary plate seems surrounded with difficulties which deter many from making trials that would he exceedingly profitable as well as interesting, and lead to more satisfactory results in the print. Many who have acquired the ability to make, and do make, good exposures, have been disappointed with the prints, which fail to correctly represent the view. The sky in a landscape is too white, and clouds are barely discernible which, in the original view, were strongly outlined. The tints and colors of a building are not correctly represented in the shadings of the print. And so we are disappointed with our work and, too many times, come to look upon photography as a subject beyond reach of those who would engage in it as a pleasure and means of developing the artistic side of our nature.

And why is this ? The answer is simple. Because we have neglected to use the proper materials for securing the results we are seeking. A few words of explanation regarding the action of the light rays upon the plate will make this clearer. All of- us have some knowledge of the spectrum; thatsunlight is composed of a combination of seven primary colors. The rainbow is but a division into the original colors of the light of the sun. The eye receives a correct impression of the hues and colors in view. Not so with the photographic plate, which is subject to chemical action when exposed to light. In the ordinary plate this action is not in true accord with the colors in the view, for the reason that some colors do not produce action which is quick enough, while others work too quickly to be in correct proportion to the view as an entirety.

The blue of the sky and the white in clouds are of about equal rapidity in their action upon the ordinary plate, thus producing a bare and unbroken sky effect in the resulting print. Red, orange and yellow, on the other hand, reflect much less light, and so do not sufficiently affect the plate, and consequently appear much darker in the print than to the eye. It is these variations from a true representation of the view that cause so much disappointment to the beginner and yet is a condition which is easily remedied by using orthochromatic plates. This does not mean that such plates should be used at any and all times, but there are many occasions when such plates will enable one to secure effects which would be entirely lacking should an ordinary plate be used. A few trials will plainly show the difference in the two kinds of plates. An instructive experiment is to take exposures of the same view on the two kinds and study the difference in the prints made therefrom. The difference between an orthochromatic and an ordinary plate is, that the former is specially sensitized to the red and yellow rays, which act more quickly on these plates and so are more nearly reproduced in their correct values.

A necessary adjunct to orthochromatic plates is a ray screen, though it is not always used when making exposures with such plates. A little study of the conditions of light at the time of exposure will determine the advisability of using it or not. The ray screen serves the purpose of reducing the intensity of action of the blue and violet rays, and fittingly supplements the use of plates that will correctly reproduce the red and yellow values. At certain times of the day, as at sunset, the blue sky is subdued by the brilliant orange or red tones of the setting sun, thus dispensing with the necessity of the screen.

In using an orthochromatic plate without a screen, the time of exposure is about the same as with an ordinary plate of the same sensitiveness. With the screen, the exposure should be increased from four to eight times, according to the degree of light. A few trials will enable one to ascertain the correct time. In one important particular orthochromatic plates differ somewhat from ordinary plates. Being very sensitive to red and yellow light, they should be loaded into holders in very dim light, which should be so shielded as not to shine directly on the plates, and the supply box should also be kept well protected. Also, in developing the same care should be used until the developer has been applied, when a little more light may safely be used. The greatest care should be used, however, in all handling until developing is well under way. The developer used should be that recommended by the manufacturer of the plates, if obtainable, and is used the same way as with an ordinary plate.

The cost of these plates is slightly more than for the ordinary kind, but the difference is not great enough to be a serious consideration, in view of the results to be secured by their use. If kept in a dry, cool place, they will keep well, though fresh plates are desirable, whichever kind are used.