There is another class of lenses of double combination, which are
called wide angle lenses. They are constructed to embrace an angle
of from 90 to 100 degrees, and are therefore indispensable for use
in confined situations, such as narrow streets and interiors. They
are also capable of being used with advantage for all the purposes
of a view-lens, their only disadvantage being that they are not so
rapid as lenses of a lesser angle. For certain subjects the back
lens of the combination may be removed and the front lens used in
the same manner as an ordinary landscape lens.
[Illustration: THE E. A. WIDE ANGLE-LENS]