THE STUDIO.
The principles underlying the action of the half-tone screen having been ex plained, the studio and apparatus may be greater as the camera is extended, decreasing as the latter is closed up ; it is greater with coarse screens, or screens having thin black lines, and less with fine screens, or those having thick lines; finally, the screen dis tance decreases as the size of the dia phragm increases, and rice vcrsii. From ,this it will be seen that the correct screen were zee and size of stop involve far too round drlculation for practical work, al cross-line he basis on which they may be necessarimt if desired has been indicated. net, and rker who desires to undertake now be considered. Any studio designed for ordinary photographic work will be suitable ; but, as the copy requires to be equally lit from both sides, the ideal arrangement would be one with a large skylight inclined towards the north, and glazed on the east and west sides, the picture to be copied being placed at the south side. Owing to the uncertainty of daylight, many workers (especially in towns) constantly use the arc light, which renders a specially constructed studio un necessary. The preferable course, how ever, if it can be done, is to have a studio available for both daylight and electric light at will. In any case, it is requisite
that the 'place selected should be free vibration (although this may be overcome, if not excessive, by suspending the camera and copy in a swing bed, or by supporting it on springs) and of suffi cient size for the camera extension and free movement of the operator. If electric light is to be used, the studio should be sufficiently high to accommo date the traversing gear of the arc lamps, unless these are worked on floor standards. Proper arrangements should be made for heating and ventilation. The developing and other operations are patterns, with different devices for ad justing the distance between the screen and the plate, are procurable, one of the best of these being the Penrose holder (Fig. 895), which is made either with ordinary carriers for dry plates, or with adjustable bars, as shown in the illustra tion, to take wet. plates, the screen dis tance being regulated by a knob outside. and indicated by a pointer moving on an ivory scale. This is, of course, a great advantage, many of the older forms of best done in a separate room or rooms, conveniently adjoining the studio.