Cameras, Lenses, and S buffers 37 



is not fitted with one, after having become ac- 

 customed to the use of it, we will discover what 

 a really invaluable adjunct it is. 



Another very useful appliance is the rising and 

 falling front, which, by changing the position of 

 the lens, without changing the position of the 

 camera, allows one to get more or less foreground, 

 as he may desire, in his picture. 



When focussing upon an object that is near by, 

 especially when we are trying to make it approxi- 

 mately life-size, it is always best to do so with 

 the back extension, leaving the front extension 

 entirely alone. By doing so we do not change 

 the distance between the lens and the object, and 

 this is very important in such close work, for it 

 is extremely difficult to obtain a perfect focus 

 when in the very act of doing so we are con- 

 stantly changing the point of focus. 



In order to take a picture it is not necessary to 

 have a lens, that is if we are always photograph- 

 ing stationary objects and the length of time that 

 we have in which to make the exposure is not 

 an important factor; but it is necessary to have 

 one when we wish to do instantaneous work. 

 A picture can be taken, however, by using a piece 

 of black cardboard, or any other opaque substance, 

 in the centre of which a pinhole has been made, 

 and which is inserted in the place that is meant 

 to be occupied by the lens. 



