12 Blli!) STUDIES WITH A OAMERA 



greater speed of the two when combined, and fur- 

 thermore, because, being of the same focus, they 

 could, if occasion arose, be used in a twin-lens box. 

 The speed of tlie combination is registered at F. (i..'i ; 

 that of the single lenses at 13.5. With the former 

 the most rapid exposures can be made successfully, 

 while the latter are sufficiently fast to permit of 

 ordinary instantaneous work. This lens is stated 

 to cover a 5 X 81 plate, and when in use on a 1 X 5 

 camera gives a high degree of illumination and per- 

 fect definition. 



The telephoto lens may be employed in certain 

 kinds of bird pliot<jgi-apliy with not unsatisfactcny 

 results. Its disadvantages are lack of speed, an ex- 

 posure of at least one half a second to a second being 

 required at F. 8 in bright sunlight, the necessity 

 of extreme care in focusing, and of absolute rigidity 

 of the camera at the time of making the exposure. 

 Ill short, the telephotograpilier needs more time, 

 both before and after pressing his bulb, than the 

 l)ird photogra])her is often accorded. However, with 

 such sul)jects as nests high in trees or on cliffs. 

 Herons and other shore-inhabiting birds. Ducks on 

 the water or Hawks perched in leafless trees, the 

 telephoto will be found serviceable. 



Negatives are frequentl}^ secured in which the 

 figure of the bird, while small, is sharp, when, by 

 enlargement, a desirable picture can lie made of 

 what in the orit^'inal was too small to bo easily dis- 

 tinguishable. An increase in size of two diameters 

 is ])f)ssible from any fairly sharj) negative, but if fhe 

 objeet be ill ])erfect focus an increase of four diame- 

 toi'S may bo made. 



