14 BIRD STUDIES WITH A CAMERA 
obtained under the same conditions with different 
lenses. 
Placing a mounted Flicker (Colaptes awratws) on 
a fence post, and setting up my tripod at a measured 
2. Lens Test No. 1. Mounted Flicker on fence post, distance fifty feet. 
Eight-inch focus, Zeiss Convertible, No. 10, Series VILa@ lens; dia- 
phragm F. 8, 3/25 second; Cramer “Crown” plate. Photographed at 
noon, in sunlight, November 30, 1899. 
distance of fifty feet, a series of test exposures was 
made, of which three are presented as follows: First,’ 
eight-inch lens (Zeiss Convertible Series VII a, No. 
10), stop F. 8, time 3!; second; second,* fourteen-inch 
front lens of the combination, stop F. 16 (equivalent 
