Igo THE FORMATION 
field is the rubber cloth. The tripod should be a happy combination of 
lightness and stability, a condition more nearly reached by the aluminum 
tripod than by any other. It should have not less than three joints in order 
to facilitate the use of the long focus upon objects near the ground. 
237. Choice of a camera. There is not a great deal of choice between 
the moderate-priced cameras of the various makers. A field camera is re- 
stricted to certain special uses, and hence is more serviceable when attach- 
ments useful only in portraiture or instantaneous work are absent. Even the 
ray filter, which has some value in the indoor photography of flowers, is use-_ 
less in the field on account of the long exposure required. From consider- 
able experience, “Premo” and “Korona” cameras have been found to be 
very satisfactory instruments. Doubtless the same statement would be 
found true of all the standard makes, but they have not been used by the 
Fig. 58. 5 x 7 “Korona” Royal camera. 
writer. “Premo” cameras are made by the Rochester Optical Co., Rochester, 
N. Y., and “Korona” cameras by the Gundlach-Manhattan Optical Co., 
Rochester, N. Y. When two or more cameras are used, the best results can 
be obtained if they are of the same make, since the details of operation are 
then the same. The reduced liability of making a blunder is often offset 
by the fact that a different pattern will permit of a wider range of use. 
Any standard brand of plates wil! produce good negatives when skilfully 
used; at least, this has been proved in the case of the Cramer, Hammer, 
Seed, and Stanley brands. Every professional photographer has his favorite 
brand of plate, but the ecologist will do well to give the various kinds a 
thorough trial, and then to invariably use the one which gives him the best 
results. Thus, while it seems to be less popular with the profession than 
the others mentioned, the writer has obtained at least as satisfactory results 
