The portrait lens must work rapidly and give the quickest possible exposure ; and this, of course, is done by designing it to work at a larger aperture, i.e., one admitting more light than is necessary for landscape work. If the portrait lens designed to work at f/4 or f/5 is stopped down to f/8, there is then no difference between it and a landscape lens working at the same aperture, given the same focal length and quality of definition. Most beginners in portraiture naturally use the lens they have been in the habit of using for their landscape, and frequently with such satisfactory results that they continue in its use - trusting to the rapidity of the plate they use for a short exposure. For, of course, a matter intimately connected with the length of exposure is the speed of the plate used - and in this matter we are much better off than we were a few years, or even a few months ago. Most of the standard makers have a selection of speeds - from slow to very fast - giving great latitude in exposure.
If we take, for instance, the Ilford Co.'s plates, we find that where their Ordinary plates would require 4 seconds' exposure for a given subject, their Special Rapid will give the same result in 3/4 of a second, their Zenith in 1/2 of a second, and their Monarch in 3/8 of a second. The cost of the plates introduces another factor needing consideration in the selection of a lens when much portraiture or figure work is to be done, and if the matter of cost is one to be taken into consideration.
As we find the most rapid plates cost from 25 per cent, to 33 per cent, more than the slower varieties, will it be worth while purchasing a rapid lens (with its many other advantages) in order that we may use slower and cheaper plates ? Each worker must be left to answer this conundrum for himself - and he will find the subject full of interesting side issues. For instance, a large aperture in a lens means a comparatively heavy lens. A whole-plate lens working at f/4 is a much more imposing piece of furniture than one working at f/8. The latter can be carried in a waistcoat pocket, and, consequently, can be used in a light field camera. The former approximates to the size of a bucket and needs a camera built like a fortress to carry it!
Some prefer doing their work in 1/4-plate size, such negatives as result in success being enlarged to a more agreeable scale. This method has its advantages and disadvantages. The economy effected is obvious - and the results obtained have a certain softness and breadth due to the enlargement. But it is certainly more agreeable to work on a larger plate. The picture can be seen more clearly on the screen and can be more easily criticised and corrected. But here, again, experientia docet, and the worker starting with such instruments as he already possesses will develop on his own lines. He may eventually become the proud possessor of a complete studio outfit - or may find that a whole-plate field camera on an ordinary tripod will do all he wants. The most useful camera I possess is a portable double extension 1-1 field camera fitted with turntable, rising and falling front, and swing back. In it I use a Ross 1/2-plate universal lens working at f/5.6 focal length. This lens, while not too heavy to be carried by the camera when fully extended, easily covers a whole-plate with a 3/4-length portrait or group, such as is illustrated in Fig. 1. By using the first or back combination alone, as a single lens, it will give a larger head than can be got on to a whole-plate, and this without distortion. The result is that working in an ordinary-sized room I can get with the same lens either a head that will fill a whole-plate, or a full-length figure in a half-plate, and anything between these two extremes. The camera itself is light enough, in its case, to be carried a moderate distance without causing fatigue, and small enough to be easily attached to the carrier of a cycle. The event that led to the purchase of this particular camera was the attempt to take portraits at home with a quarter-plate magazine camera which possessed no focussing screen, and could not be racked out to focus anything nearer than 4 yards. This was balanced on a chair, and the exposure made with more hope than faith. Preliminary experiences of a similar kind will doubtless lead others to realize their requirements.
The absence of a studio proves an obstacle to many who would like to do portraiture. But those who do not possess a specially-lit studio for their work are not under such a great disadvantage as might be imagined. The lighting of an ordinary room is quite capable of affording good results, and with the aid of simply-contrived curtains and reflectors can be made to suit almost any purpose. And when the possessor of a camera has experienced the joy of making a passably good figure picture, he will discover that his domestic surroundings are full of interesting lightings and pictorial suggestive-ness. Further, he probably has a garden or some open air space at his command which can be enlisted in the service of his art, and no better place than the open air can be found in which to start portrait work, and this for two reasons. In the first place, the problem of lighting is beyond the control of the operator and need not, therefore, trouble him. And, secondly, the question of the correct exposure can be easily ascertained, and will, at the same time, be found to be much shorter than would be necessary indoors. These two facts will make the first essays easier, and will enable the beginner to concentrate