CHAPTEE III. 



OBJECTIVES CONTINUED. 



What constitutes a really superlative wide-angled 

 objective? It has been our fortune to reply to this 

 question upwards of ten thousand times, and it may be 

 true that no two of these responses have been exactly 

 alike. In the present essay let us get close to the reader, 

 introducing a little gossip, and, at the same time, seek- 

 ing a little relief by avoiding expressions which are 

 getting to be stereotyped, such as the " writer," 

 "this," " the author," "that," etc., helping ourselves 

 freely to the first person singular, about as one would 

 when writing to a friend. 



It has been already shown that there are two classes 

 of high-angled glasses namely, those having balsam 

 apertures, say up to 100, the other class responding to 

 air angles, up, say, to the " impossible," 180. And, 

 first, let us consider the objective ol high balsam angle. 



I have, in advance, stated that these glasses necessa- 

 rily have a very short working distance. But this re- 

 mark must not be swallowed whole; let it be taken 

 rather with a "pinch of salt," keeping this little fact 

 well in hand, that there are wide-angled balsam aper- 

 tures, having greater working distance than will be 

 found present in other objectives of the same nominal 

 focal length, and having, too, no really wide air angles. 



137 



