92 Photography for the Sportsman Naturalist 



will probably do, but as he advances he will find 

 that it is inadequate for the various uses to which 

 he may wish to put it. In most branches of work 

 speed is necessary, as is also depth of field and 

 definition. All these qualities are combined in the 

 highest possible degree in the best lenses. The 

 longer the focus of your lens the better, and it is 

 always well to get a lens that will cover a plate 

 one size larger than the plate you intend to use. 

 By doing so you acquire greater length of focus 

 and greater covering power, which is useful where 

 the rising front of the camera is used. 



A short-focus lens distorts objects that are close 

 to the camera, often to such an extent that the 

 results are grotesque and ludicrous in the extreme. 

 Unfortunately those lenses of the very highest 

 speed have the least depth of field, and I would 

 advise that for all-round use one working at about 

 F.6 be used. This gives sufficient speed for all 

 work, under ordinary conditions, combining with 

 it a fairly considerable depth of field. The best 

 lens is one whose two systems of combinations 

 have different foci and can be used separately. 

 In such an instrument we have practically three 

 lenses in one, the front combination being of one 

 length of focus, the rear of another, and the entire 

 lens, or couplet, of a third. Of course the single 

 combination is much slower than the double, and 

 this must be taken into consideration when using it. 



