79. Orthochromatic Plates

Orthochromatic Plates. Where tone effects are desired, such as the proper rendering of color values of a house, the orthochromatic plate is indispensable. The orthochro-matic plate is sensitive to green and red, so where these two colors predominate this plate may be used to good advantage. For example, brick buildings surrounded by green lawns photographed with an orthochromatic plate will give better values than if the ordinary plate were used.

80. Isochromatic Plates

Isochromatic Plates. The isochromatic plate is more sensitive to green and yellow. With either of these plates much clearer sky effects can be obtained. Clouds may also be more readily preserved with these special plates than with the ordinary kind. However, until one becomes familiar with the values of special plates, it is advisable to use the ordinary fast plates.

81. Exposure

Exposure. Before making the exposure, one word more of advice as to focusing. All architectural views should be absolutely sharp. We advise, therefore, the stopping down, or the using of diaphragm F. 16, or U. S. 16. Sometimes with a cheaper lens where the lens has not the covering capacity, and it will not cut sharp to the edge, it is necessary to stop down to F. 22, or U. S. 32. The exposure necessary is, therefore, governed first by the conditions of the strength of light and shadows in the view and second by the size of the stop used.

82. There are a number of exposure meters in use, also tables of rules governing the length of exposure. We do not recommend adopting either of these. On the contrary we advise the keeping of a memorandum of all exposures, conditions under which they are made, size of stop, etc., and allow past experiments to be your guide for future exposures. By carefully following instructions one will soon be able to judge the proper amount of exposure necessary to produce the best results. You must be governed, however, by the following rule: If you are stopping down to U. S. 16 and are giving 1/4 second exposure you must when using stop U. S. 32 give four times the exposure at least, or 1 second. Usually 1/4 to 1/2 second is sufficient in a bright sunlight with a medium stop. The higher the number on the stop the smaller the opening, consequently, a longer exposure must be given. When more than 1/4 second exposure is required, we advise the use of bulb exposure. With the bulb exposure, by pressing the bulb the shutter is opened, and when releasing it, it is closed. You will soon accustom yourself to measure the time required very accurately and by instinct open and close the shutter properly.

83. Developing

Developing. In the developing of an architectural view the most essential point is to produce a negative with snappy highlights, shadows clear, but filled with detail. Avoid flat negatives. We recommend, in addition to the regular formula for developing given in Volume II., that you use a few drops of a 10 per cent. solution of bromide in the developer. This bromide adds snap to the highlights and the shadows are held clear throughout the developing. If you find the plate slightly under-timed reduce the strength of the developer by adding double the quantity of water. Never under-develop an architectural view. It would be far better to slightly over-develop and then, if necessary, reduce the plate after developing.