391. Level

Level. It is essential that all lines be absolutely-perfect, and for this reason the camera should be accurately leveled. Although it is possible to judge approximately on the ground-glass when the lines of the building are rectilinear, yet a small pocket level, which will enable you to set your camera perfectly plumb, should form a part of the equipment.

392. Time Of Day And Light Conditions

Time Of Day And Light Conditions. First of all, an exposure should not be made at a time of day when it is necessary to point the camera directly toward the sun. An hour should be chosen when the sun is to the rear or to one side of the instrument. Veiled and foggy negatives would result if the strong rays of light were permitted to strike directly, or even indirectly, onto the lens or interior of the lens barrel. Usually it is preferable to have the sun to one side of the camera, for in this position it will cast shadows, which will give relief to the various parts of the structure, and also materially aid in giving a more adequate idea as to the character of the most minute details. It is more preferable to make the exposure when the sun is under a cloud than to do so when the piercing rays cast extremely heavy shadows. With this latter lighting effect the high-lights will be extremely hard, and the detail in them lost, if enough exposure is given to secure a record of the detail in the deeper shadows.

393. It is, of course, necessary to make the photographic records at stated intervals, and for this reason it may not always be possible to work under the most favorable conditions; but if the photographer will, with the superintendent of construction, lay out a systematic plan for making the series of records, objectionable lighting effects may be almost entirely eliminated, as the most favorable time of day may be chosen in which to make the exposures.

394. Exposure and Development - The exposure will depend, to a great extent, upon the lens, plate, size of stop, and weather conditions, as well as the nature of the subject being photographed. Full exposure must in all cases be given; under-exposure would result in a negative lacking detail in the shadows. This latter is undesirable, as it is essential that even the most minute detail be shown in the construction photograph. It is far better to slightly overexpose the negative, for by exercising proper judgment such a one can be very easily controlled in the development, and even though the resulting print may be a trifle flat it will contain a detail record of facts.

395. In cases of known over-exposure, the development should be so handled as to enable a negative of proper contrast and gradation being secured. Full instruction regarding the handling of over-exposures is thoroughly covered in Volume II.

396. When the extreme of exposure has been given, it is preferable to carry the development beyond the normal-stage, and then, after fixing, reduce with the potassium ferricyanide reducer. (See Volume II.)

397. The suggestions contained in these chapters on construction work should be most carefully studied, as they are based upon the practical experience of one of the largest engineering companies in this country. The securing of detailed interior photographs is covered in Chapter VIII, which gives instruction on the photographing of machinery and all interior details.

398. Finishing The Prints

Finishing The Prints. It is preferable to finish the print on glossy paper - either a developing paper or a printing-out paper. The method of mounting for the record files is comprehensively shown in Illustration No. 83, which is a reproduction from the regular blue-print diagram supplied photographers by the Arnold Company, of Chicago.

399. Volume IV contains detailed instruction regarding the printing and finishing of all classes of photographic papers.