CAMERA NOTES.

Manawatu Herald, Volume XXXIV, Issue 1042, 21 December 1912, Page 4

CAMERA NOTES.

[By “Focus.”]

That the matter of “exposure” is the most important, the basis on which rests the technical quality of the resulting photograph, and on the correctness of which depends the ease with which all subsequent processes follow, no one of experience can deny, and its importance seems to be greatly magnified by the fact that the mental calculation of approximately correct exposure under widely varying conditions is a faculty which can only be fully developed by a good knowledge of the governing rules and close study of conditions of light and results obtained under all conditions. THK ADDKHSS. An interesting address was delivered at the Camera Club meeting on Tuesday evening on this subject, and owing to its paramount importance in good photography, I shall endeavour to give a brief resume of the more important portions of this lecture. After briefly introducing his subject, the speaker touched on the relation of apparatus to exposure. The action of variations of the atmosphere caused variations of alleged shutter speeds, a fact too often detrimentally demonstrated in very high speed shutter work. For exposures of moderate duration the atmospheric action may be considered uegligable. Of course, the effect of cold or heat varies according to the mechanical construction of the shutter. The one pattern susceptible to temperature variations is that known as the “roller-blind.” Indicated rapid shutter speeds are seldom accurate. Another matter having an important bearing on exposure, pointed out by Mr Teviotdale, was the use of the iris connected with the lens. The Royal Society, shortly alter this form of diaphragm was introduced by optical manufacturers, set down a scale of standard apertures for lenses, each respective aperture, from f/4 to f/32, decreasing the volume of light rays passing through the lens by one half, and consequently doubling the exposure, THK LIGHT. The lecturer set out in a simple and intelligible way the rules governing light in respect to this important matter. They were, briefly, intensity of light and quality of light. The human eye is an unsatisfactory instrument to rely on in gauging the intensity of light, owing to the nervous control of the volume of light allowed to enter through the iris, and the tendency of the eye to as far as possible allow the same amount of light to pass into its interior during cloudy weather as when the sun is shining brightly. To overcome this, mechanical instruments may be obtained which will guage the light correctly enough for all practical purposes. The estimation of light is the most important factor in correct calculation of exposure. Light decreases in actinic value as the hours of daylight decrease, so much so, indeed, that the failure of many amateurs to meet with equal success in their exposures during winter as in summer is wholly accounted for through insufficient allowance for the difference in the intensity of summer and winter light.

DISTANCE AND NATURE OE SUBJECT. The effect of distance and nature of the principal object in the photo, must receive due consideration. The matter of distance is cut up into near foreground, middle distance, open foreground, and panoramic views, with several varieties of lightness or heaviness of the subject. The rule to observe is, the nearer the object the longer the exposure—half the distance twice the exposure. MECHANICAL AIDS. The use of an exposure meter or calculator was advised by the lecturer, by the aid of which, and the exercise of a little discretion, the correct exposure may be arrived at with ease. The ill-effects of errors in exposure were illustrated by photographs, and bore convincing testimony of the value ol correct calculation in this important period of the picture making process.