THE CAMERA For outdoor and landscape photography the type of camera, to be used on a stand and technically known as a " Field Camera," should be of fairly light construction ; but at the same time sufficiently strong and compact to bear occasional rough usage with equanimity. It is no longer the fashion to carry into the field instruments of the whole-plate or 10 x 8 in. size; cheap and expeditious methods of enlarging have changed all this ; and the featherweight patterns of a dozen years ago are now unnecessary. The half-plate x 44 in.) may now be regarded as the limit for direct printing, and many operators are content with the convenient 5 x 4 in. and quarter-plate (44 x 34 in.). Of course we will not deny the advantages of the whole plate and 10 x 8 in. cameras to those who make a speciality of architecture.
Extension of Camera.—In choosing a camera one of the first essentials is to see that it will provide for the various lenses likely to be used in it. There must be double exten sion, focussing by rack work sufficiently to allow of the back or front combination of the rectilinear lens being used alone, when the central features of the view are at a considerable distance. In the case of a half-plate instrument the extension necessary will be from i6 to i8 inches. On the other hand, provision must be made, by a telescopic form of baseboard or otherwise, for a wide-angle lens of about 5 inches. If the baseboard is long, the lower part of the view is liable to be cut off. Modern patterns provide hinges and spring catch, so that the baseboard can drop down over the tripod legs.
Swing-Back.—It is frequently necessary in order to secure some particular view, especially in a confined space, to point the camera upwards or downwards. If, however, the plate is left in this position, the result would be a picture with the lines absurdly distorted. This difficulty is obviated by the use of the swing back fitted with a level, enabling the dark slide to preserve the perpendicular whatever the angle- at which the camera is tilted. Some cameras have also a side swing, but this is rarely required.
Rising and Swing Front.—This valuable modern inven tion almost does _ ------ clWay with neces sity of the swing back. The camera itself need not be moved out of the perpendicular while the lens is raised or lowered and pointed in the required di rection. Bellows of extremely tapering pattern are unsuitable for use with the rising front, as a portion of the picture may be intercepted, and this form of bellows must be fitted with a ring or tape on one of the central folds to draw the bellows forward when using a lens of short focus. A changing back enables the advantages of swing back and rising front to be applied to both upright and horizontal shaped views.
The accompanying figure shows a newly introduced pattern of rising front, in which however much the lens is raised it swings on its optical centre, so that the centre of the circle of illumination is always opposite the centre of the plate. No danger need therefore be apprehended, when
the front is tilted to get in objects that are extremely high, that the plate will be unevenly covered and that corners will be in consequence left unexposed.
From time to time camera and bellows must be examined to see that there is no leakage of light. The inside of the bellows and surrounding woodwork ought to be dusted occasionally, and any trace of shininess owing to wear cured by a coat of dead black varnish. Light reflected from the lens on to the bellows is a frequent cause of fogged plates. Leather bellows have a tendency to split if not occasionally varnished outside. For hot climates teak is the best material, and every angle in the wood work should be protected with brass binding ; Russian leather bellows will resist for a long time the attacks of white ants and such-like enterprising insect life.
Focussing Screen. — The screen should be of finely ground glass. In old-fashioned cameras the glass is often of a bluish tint, and this was no mean advantage, as the operator was less likely to be misled by the colours of his landscape which failed to reproduce themselves on his tone print. The ground-glass side of the focussing screen and the film of the plate in the dark slide must be in accurate register. If any doubt exists on this point it may be settled by putting the screen into one of the dark slides and focussing the object, then compare the result with the ground glass in its usual position. When the slides are of the solid pattern the test must be made by careful measurement. Plate and Film Holders.—Three double-dark slides are usually supplied by camera makers to fit with the camera into a satchel or travelling-case, and the pattern of instru ment selected will probably determine that of the plate holders, whether of book or solid form with leather-hinged shutters folding back when opened, or with celluloid shutters wholly withdrawn during exposure. The two great dis advantages of the celluloid shutters are (I) that the material has a marvellous attraction for particles of dust, so that plates can never be kept in the slides for longer than a few hours at a time and (2) the danger of breakage while the shutter is resting in the coat pocket or elsewhere during ex posure. Metal is occasionally substituted for the celluloid ; if it will not break, it will bend out of shape under pressure. Dark slides of all patterns require overhauling at times. The velvet in the light traps becomes dry or frayed, and shrinkage will take place with the very best material. Avoid all " bag" changing boxes. They have brought the changing box into disrepute. But a very reliable one for twelve plates is made on the automatic slide principle, the fresh plate or film being brought into position by simply drawing out the telescopic inner body and pushing it home again.