16 



BIRD STUDIES WITH A CAMERA 



son, we observe that the eight-inch gives a fairly 

 wide field, excellent depth of focus, but a very small 

 image of the bird, for which alone the picture has 

 been made. With the f ourteen-inch we decrease the 



. ,, 



4. Lens Test No. 2. Same subject, distance, plate, and date as Test No. 1. 

 Front lens (fourteen -inch focus) of Zeiss Convertible, No. 10; dia- 

 phragm F. 1 6 ; l / 25 second. 



extent of the field nearly one half and almost double 

 the size of the object pictured. This, however, has 

 been done at the loss of depth of focus, not even the 

 first of the line of posts running directly into the 



