14 T H EB *A-0 D+U"B ON © BSU Lebo Tae 
Test Your Binoculars 
By JOHN HELMER 
ABOUT THE ONLY WAY an ordinary user can test the performance of his 
binoculars is to compare them with others of known quality. To test the 
ones we get for Audubon members, we check them against a Bausch & Lomb 
7x35, taking them out of doors where we can set up the front page of a 
newspaper in shade at about 75 feet. When the smaller headlines are ex- 
amined closely, we can see whether they are read more easily with one 
binocular or the other, or whether one gives a brighter image. Because the 
eyes are so thoroughly trained to recognize characters in print, this makes 
a good practical test of sharpness, or “definition.” Any one can make the 
test. A sharply defined and bright image is what you should have. Also notice 
whether one binocular has a wider field of view than the other. 
You can check your alignment at the same time. Just hold the binocular 
still, shut one eye for an instant, then the other, alternately, while looking 
at a small object. If the image jumps up and down, your glass needs fixing. 
That is very bad for the eyes. 
Wouldn’t it be a good idea for your local club to set up a binocular test- 
ing range on one of its field trips? You need only a folding table and chair 
for the observer and the newspaper at a distance, during the lunch hour. 
You may find the glass you use is better than you think. If you have some- 
thing like a good old pre-war Zeiss or Leitz or B. & L. that is not especially 
bright because it is not coated, don’t worry about that. And it doesn’t matter 
much whether it is large or small, center focus or individual, 6x magnifica- 
tion, 7x or 8x. It’s the built-in quality that really counts, as always. 
847 Ridge Ave., Evanston, Ill. 
Bh fi fi 
Book Reviews 
SEEING AMERICA’S WILDLIFE IN OUR NATIONAL REFUGES, by Devereaux 
Butcher. Devin-Adair Co., New York City. Cloth, $5.00; paper, $2.50. 
One of the most eagerly-awaited books of the season has finally come off 
the press. This is the first popular book ever written on the national wild 
reserves of our country. Covering more than 270 separate areas, crossing 
thousands of square miles from Maine to Oregon, and from the Florida Keys 
to Alaska, Devereaux Butcher has come up with a book you will surely en- 
joy and want to present to your friends. 
During certain times of the year, some of these refuges contain up to three 
million wildfowl — ducks, geese and swans. Other areas help preserve the 
habitat of the trumpeter swan, the whooping crane, and huge mammals like 
moose, bison and bighorn sheep. 
