BIRD PHOTOGRAPHY G05 



For photographing birds, the outfit must be of a more special character to deal successfully 

 with all cases. 



The camera should be strongly built, to ensure absolute rigidity; this is an important 

 point, as there is sure to be more severe wear than in ordinary photography. As it is frequently 

 the case that the front of the tent, or some branches, or whatever is used for concealment, will 

 be fastened to the front of the camera, allowing only the lens to project, which makes it undesir- 

 able to move the front in order not to disturb the concealing material, it is an advantage to have 

 a camera the back of which racks out for focusing instead of the front, as on the usual form. 

 For this reason, and also for its rigidity, the old square field camera is excellent. 



A form of field camera, however, now made by most firms, and known as " triple extension," 

 is good in that both front and back rack out. With such a camera the focus can be roughly 

 adjusted by a moderate extension of the front, the concealing material affixed, and further 

 focusing carried out by racking out the back. This form of camera is additionally useful, 

 owing to the very long extension possible. This is important, as when photographing a near 

 object with a lens of the usual focal length a long extension is necessary. But in order 

 to secure a fair-sized image of a small bird, it is necessary that the lens should be of longer 

 focus than usual, necessitating a corresponding increase of camera extension. The standard 

 sized cameras suitable for this work are half-plate 6J x 4|, 5 x 4, and quarter-plate 4{ x 3J, and 

 the lenses generally fitted are 8", 6" or 7", and 5" or 6" respectively. For bird work these are too 

 short, and I recommend 10", 8", and 7". 



The serious bird photographer will find it convenient to possess a camera of each of these 

 three sizes. For large birds and indeed for all in such places where weight and size of 

 apparatus is not a serious disadvantage the half-plate size is the best, as a good sized image of 

 the bird can be obtained without placing the camera too near to the nest, and the size of the 

 plate allows the inclusion of a reasonable amount of surroundings. The 5x4 camera being 

 considerably smaller and lighter, is more portable for less accessible localities, and the quarter- 

 plate is an excellent size for nests. Although in photographing nests, movement owing to wind 

 occasionally makes a short exposure necessary, as a rule it is possible by waiting for a lull 

 when the herbage is still, to give one or two seconds. This with a rapid plate enables the use 

 of a comparatively small lens aperture, small enough to bring all the most conspicuous parts 

 of the surroundings into sharp focus, so that the resulting negative will enlarge satisfactorily 

 to any required size. 



For birds, however, the quarter-plate is not large enough to give the best results, and should 

 the beginner wish to confine himself to one camera, the 5x4 size with an 8" lens will be found 

 the most generally useful. I use a 10" lens on my own 5x4 camera and find it very valuable. 

 It should be borne in mind, however, that the depth of focus in the subject photographed 

 decreases with an increase of the focal length of the lens. In other words, if two lenses, 

 one 8" the other 10", and both of an aperture of /6, are focused on the same subject, although 

 the 10" will give a larger image, yet a greater depth of the subject will be in sharp focus 

 with the 8" lens. Therefore, if the outfit is to be limited to one lens, 8" will be found the best 

 for general work. As 8" lenses are made to cover sharply a plate 6 x 4f , it follows that when 

 used on a plate 5x4 the covering power of the lens is not taxed to its limits, so that even a 

 moderately good lens is sure to cover the smaller plate. Whatever make of lens is selected, the 

 full aperture should be not less than /6, as although the conditions will generally allow of a 

 smaller aperture being employed and when working at a nest on the ground /ll or /16, or even 

 smaller may be necessary to secure a desirable depth of focus yet there are occasions when a 

 bad light, a restless bird, or the depicting of attitudes involving movement, demand a very short 

 exposure : it is then that the value of the large aperture is appreciated. 



As a general rule the larger the aperture the more expensive the lens. But it should be 



VOL. IV. 4 H 



