The photographer who may be expert at landscape or architectural work, will find himself at a loss when he essays portraiture. For apart from the art of managing the sitter (a most important element in producing a successful result), he will soon find that the kind of plate that is suitable for outdoor work does not answer well for portraits, unless the developer is greatly modified, for quite a different kind of negative is required. As a general rule it is advisable to use very rapid plates for portrait work; and in this respect, at the present day we are much better supplied than even five or six years ago, and with an extra-rapid plate it is possible to secure a fully exposed negative in half a second, in weather and under lighting that was quite impossible ten years ago. The best expression and pose are generally secured when the sitter is unaware of the actual moment of exposure; and for this purpose a silent shutter working inside the camera is best. The sitter should never be asked to keep still unless, in groups, and when circumstances necessitate a long exposure; and nowadays an exposure of five or six seconds is a long one. Every effort should be made to put the sitter quite at ease.
A head-rest should not be used unless absolutely necessary, and few photographers are aware how easily it can be dispensed with, and fail to realize how strong an objection nearly every sitter has to it. It is far better to have an occasional plate spoilt by working without the rest than to make every sitter uncomfortable by its use. In fact some portrait negatives are actually improved by a slight movement. In a special kind of lighting when the face is in shadow relieved against a light background, a slight movement which produces the effect of diffusion of focus greatly improves the result.
Great care must be exercised in choosing the background even when it is only plain or graduated, and it is well worth exposing three or four plates on the same sitter, in the same position and lighting, and with the same exposure, but with different backgrounds, and then carefully comparing the resulting prints. Even if only one background is at hand its depth can be varied by placing it nearer or farther from the source of light. The background must also be selected to suit the lighting of the sitter, as a background of medium tint suitable for what is called "ordinary lighting" would be quite unsuitable for "Rembrandt" effects, or where strong contrasts of light and shade are used, when part of the face is in dark shadow. For such effects a dark background is usually best, as it gives luminosity to the shadow side of the face. But such dark grounds are not suitable for "ordinary lighting" where the face should be full of delicate half-tone, all of which would be killed by the strength of the dark background.
For the Rembrandt effects a much longer exposure is necessary as less light is reflected from the face on to the sensitive plate; they will often need twice or three times as much as for ordinary portraits.
When pictorial backgrounds or accessories are used it must be remembered that the object of the photograph is to secure a portrait of the sitter, not to show what a large stock of accessories the photographer possesses. It is best to use as few accessories as possible; I have heard a lady complain bitterly of a well-known photographer, who having posed her in a very difficult position, kept her waiting for five minutes while he arranged a screen, a palm, a footstool, a tiger-skin, etc., so that she felt positively ill before the exposure was made. The sitter should not be kept waiting in the pose to be photographed any longer than is absolutely necessary. If accessories must be used they should be simple and suitable.
When portraits have to be taken in ordinary rooms it is advisable to get a friend or assistant to experiment upon, if possible beforehand. Even a few minutes spent in studying the possibilities of light and arrangement of furniture will save a great deal of worry when making the actual exposures, and nothing upsets nervous sitters more than having all kinds of experiments and arrangements made with them. But it is sometimes well worth wasting a few plates on exposures which the photographer thinks will be useless, in order to give the sitter time to get accustomed to the room; it must not be done in a fussy, irritating way, but rather to show that it is not such a very dreadful operation and really "doesn't hurt." This plan often works well with nervous children, who soon become accustomed to the room and the photographer. There is a great deal to be said in favour of the maxim "leave your sitters alone." The photographer must cultivate quick observation so that he sees at once a good pose, and secures it; and here again quick plates are essential, as many of the most charming poses are caught unexpectedly. It has been well said that the best poses the photographer secures are those he observes, not those he creates. But a spontaneous pose may not be quite perfect and a slight alteration may be easily made without disturbing the rest of the figure. It will generally be found that a pose that takes a great deal of arranging is not a success.
When taking portraits in an ordinary room it is usual to place the sitter near the window, so that one side of the face is strongly lighted and the other in deep shadow, and then use a white reflector to light up the shadow side. It is often better, when the window is a large one, to place the sitter farther back in the room almost facing the window, and put the camera near the middle of the window looking into the room; a softer lighting will then be secured. For outdoor portraits a shady corner is best, and if possible, one where the side light is much subdued on one side; a light head-shade may be used with advantage. A large grey rug out of focus makes a good background; a blanket is too light.
A portrait lens is best for the work; but if the photographer does not possess one, he need not despair of producing good work. A rapid rectilinear lens used at a large aperture will answer the purpose well; it should always be used at full aperture, partly for the sake of quickness in exposure, and partly to prevent accessories and parts of the dress appearing too sharp and competing in importance with the face. Subordination of parts is one of the essentials of a picture; and if we examine a good portrait we shall find that probably no part of the photograph is quite sharp except the eyes and face. Otherwise the less important details are apt to obtrude themselves on our notice. A stop will generally be necessary, however, with a portrait lens if a full or three-quarter length is to be taken, and it will be found that heads only (as a rule) can be taken at full aperture. Just as good work, however, can be done with a rapid rectilinear as with a lens specially made for portraits, except where rapid exposures are to be made; but it is necessary to use one of fairly long focus. A rapid rectilinear lens used for landscape work on a half plate would be much too short in focus for giving good portraits on the same sized plate, for in order to get the figure large enough it is necessary to place the camera so near the sitter as to produce distortion. For portraits on a half plate a lens of at least nine inches focus should be used and for a whole plate not less than sixteen or eighteen inches, and longer if possible.
The swing back of the camera will be found useful in portrait work for getting parts of the figures into focus that are either too far behind or too far in front of the plane of the face. For instance, a full-length figure leaning back in a chair will have the feet out of focus when the face is sharp if the back of the camera is vertical, and this applies with even greater force to groups. A side swing too is useful, but is not absolutely necessary. Even in bust portraits the swing back is useful in getting the shoulders in focus when using a large aperture, for although it is well not to have the whole of the figure in perfect focus all over, it is not advisable to have the face sharp and the rest so out of focus as to be blurred.
The development of a portrait plate should be different from that of a landscape, because a different kind of negative is required. A rapid plate developed so as to give a soft delicate image is best; and a developer containing more alkali and less density giver is good, and it may be considerably diluted with advantage. The image should appear within ten seconds of pouring on the developer, and the negative will generally be developed to sufficient density in from two to three minutes. With a good average rapid plate the image should show fairly well on the back of the plate, but this and the time of development will vary so much with different developers, and with the taste of each photographer that no hard and fast rule can be laid down.