This section is from the book "The Barnet Book Of Photography", by Herts Barnet. Also available from Amazon: The Barnet Book Of Photography.
I have devoted more space to motive, and shall give less to actual methods than perhaps the beginner would wish, yet the apportionment which I have adopted I believe to be best, and at least agrees with what I believe to be their relative importance. The methods which the photographer bent on expressing his impressions of Nature may adopt in attaining his end are elastic, and are limited perhaps only by his own resourcefulness in contriving to modify and apply the technics of the process, as he has learnt them through chapters devoted to exposure, development, and the like. That a more or less complete mastery of technicalities is essential goes without saying. Unless one is born a genius (and the Barnet Book is not intended for such), one cannot render Beethoven or Mendelssohn until long after mastering the elements of music, or paint without learning how to mix colours, or speak and write without grammar; and for that reason this article on pictorial photography is placed last in the book. So now, in setting up the camera and looking on the focusing screen, or it may be looking into the finder of the hand-camera, we see the scene which for some reason or other we have selected. Now, to use a hand-camera for pictorial work—and it may so be used—implies previous training with an instrument in which the image can be seen and focused whilst it is seen. Having thereby learnt roughly the distance and lens aperture best suited for typical occasions, one may work with a focusing scale and guess-work ; but there must ever be a degree of uncertainty. The size of the camera matters not, nor its pattern, nor the lens used, so long as we can see the image precisely as it will come on the plate and place the sharpest degree of definition precisely where we desire.
Supposing, then, we have racked out the camera so that the view is reasonably sharp ; the diffident one may ask, "What shall I focus sharpest, or what stop shall I use?" So far as the lens stop influences the exposure, this is dealt with in the article on Negative-making, which comes first in the present volume ; but, so far as the effect which any particular stop produces, and the appearance attained by focusing sharply on one particular plane, or securing sharp definition throughout the picture, or, as it is termed, " depth of focus," the reader should have perceived by this time that it is a purely personal matter, one for individual taste and judgment to decide. The general suppression of sharp focus, the fuzzy picture, is not more artistically right that one in whicH everything is critically sharp, unless by such suppression an effect is obtained which could not be as well rendered by any other means.
It is veritably a case of the end justifying the means, and, whilst there is no rule, no question of right or wrong in the matter of focusing, it will perhaps at first be found expedient to avoid either extreme. As the principal object of the scene is naturally placed more or less in the centre of the picture, and light and shade, as well as other objects, and the chief lines in the composition are, as far as possible, so arranged as to concentrate attention on that principal object, it will probably be but natural to first focus sharply upon it. We thus give it chief attention. Do this, then, with the lens at open aperture—that is, without any stop at all j probably objects beyond and those close to will be so confused and blurred as to be hardly recognisable, and if the picture were made like that it would be unpleasing, and the spectator would be made conscious of imperfection or incompleteness. Next try the effect of the largest stop. Suppose it to be f 8, and if this does not sufficiently clear away the regions of blur and confusion tryf11, closely studying the altered effect on the ground glass, and determining thereby the precise degree of sharpness and depth best calculated to produce—what ? A precise copy of all the facts and details in the view ? No, certainly not, but that degree of sharpness which promises to suggest in the finished print the impression which the original produced in your imagination.
This may sound impossible until you begin to consider it more closely. For instance, suppose that one tree amongst the many which form a beautiful grove by reason of its form, its light and shade, or some other character, attracts your notice and pleases you; instantly, for the time being, this occupies a central position in your thoughts; indeed, the entire universe is mentally grouped around it. Other trees, although as large and as distinct, are in your thoughts quite subordinated ; you are conscious of their presence, but only in a vague sort of fashion. Hence, were you to focus all equally sharply, so that on looking at the print the spectator feels them all to be equally pronounced, this will not give particular prominence to the one object which was chief in your imagination. This is but one rather crude example, but it may suffice to show what is here meant by making the picture realise the mental impression or imaginative idea. As a general rule, although, as has been said, there can be no fixed rule, it will be found best to focus most sharply on whatever object forms the principal theme—the raison d'etre—of the picture, and let other objects, other plants, be just so much less sharp as shall cause them to be subordinate, yet not so unsharp as to make the want of definition immediately noticeable.
In landscape subjects, when we have perhaps an attractive foreground very close at hand which we wish to render well defined, but to do so and at the same time secure moderate sharpness in the rest of the picture would necessitate the use of a small stop, which possibly movement due to wind prohibits because of the consequent long exposure— in such case the swing back of the camera is a most valuable accessory. By swinging the top of the back outwards we may get the foreground quite sharp, as well as the distance, with even the largest stop. Similarly, a side swing is often useful when on one side of the picture we have a flowery bank or bed of reeds which come very close to the camera.
 
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