Early Work In Photography
A Text-book For Beginners

72 Early Work in Photography. To bring it into action, we must release the tension of the milled side screws (which hold the back of the camera at right angles to the board) and then push the top of the focussing screen towards the lens until the bubble of the level is in a central position; or a plumb line, as shown in the sketch (fig. o) may be used; this will indicate directly the screen is "plumb," or upright. When the screw is in its correct position, the screws must again be clamped and the image examined on the screen. The student will now observe that the upright lines are all perpendicular, but the focus of the image is not equal all over the screen, this is because one part of the screen is nearer to the lens than another. We can equalise this focus only by very careful adjust ment of the focussing screw and the use of a small stop. We advise the student to try several experiments in such focussing, and count the time well spent when he has learnt to set up his camera opposite a high building and focus it correctly on the screen within p0c 1060i Fig. 9. Fig. io. twenty minutes. When the screen is correctly adjusted, the lines of the building will all ap- pear truly upright on the screen, as T . shown in fig. io. It sometimes happens (though not often, unless with a very careless worker) that the back of the camera is set up "out of plumb” in the other direction (i.e. sideways) as shown in fig. n; it is best to remedy this defect by moving the tripod legs—which is easily done if the tripod be properly set up. A variety of opinion seems to exist as to the best way to set up the tripod—many writers favouring the method of having one leg beneath the front of the camera and two at the back. Although at first sight, this may seem the simplest plan owing to the ease with whicli the student may approach the focussing screen, we cannot say we favour it at all. We much prefer to adjust the tripod so that one leg falls exactly beneath the centre of the focussing screen. The camera may then be almost instantaneously levelled by sliglitly moving tliis back leg in one direction or another. rurtheimore, we do not find it cause any inconvenience