Cameras, Lenses, and Shutters 45 



dirt of any kind, and grease as possible ; and in 

 handling them the fingers should never be al- 

 lowed to come into contact with the surfaces of 

 the glass. When cleaning them, which should 

 be frequently done, never use anything that is at 

 all rough, for the glass of which a lens is made 

 is comparatively soft and, consequently, easily 

 scratched. Chamois is not a good thing to use. 

 An old piece of silk or very soft old linen or 

 muslin is good, but better still is the soft paper 

 that is manufactured expressly for this purpose, 

 and which can be obtained from any dealer in 

 optical goods. The paper from which Chinese 

 napkins is made is also good. 



In cleaning a lens do not scrub it as you would 

 a window pane, but rub it very gently with a 

 circular movement around the lens. If there is a 

 dirt spot that cannot be removed by simply rub- 

 bing, then either breathe gently upon it, or use a 

 drop of alcohol, which must immediately be dried 

 off. On no account ever apply water, ammonia, 

 or any chemicals. 



Lenses deteriorate with age, especially when 

 left exposed to the light or air, and so they should 

 be protected as much as possible. Chamois bags 

 or round cardboard boxes are good receptacles for 

 them, and, when they are out of the camera, they 

 should always be capped at both ends. 



In fitting a flange to the front board, one should 



