LENSES 



camera, and would make things extremely unpleasant 

 for the photographer if they found themselves the 

 subject of his attention. 



As far as telephoto lenses go, I have not had a 

 great deal of experience, but the one I have used 

 during the last two years has given me complete 

 satisfaction. It is a Dalmeyer No. i Grandac. 

 With a camera extension of 1 2 inches, and working 

 at the large aperture of F/12, it gives the equivalent 

 of a lens of 30 inches focal length ; that is to say, that 

 at 60 yards it gives the same sized image as an 

 ordinary quarter-plate camera and usual lens (5 inches) 

 gives at 10 yards. A greater number of magnifica- 

 tions can be obtained by increasing the extension of 

 the camera, but this, of course, decreases the amount 

 of light transmitted. The positive of this telephoto 

 combination is of 10 inches focal length, and works 

 at F/4, so that it is admirably adapted for very high- 

 speed work, and also for photography when the light 

 is very poor. Its one disadvantage is its great bulk 

 and weight. 



Plates or films can be taken, but the former are 

 far more reliable, and although much heavier and 

 more inconvenient, the finer results obtained far out- 

 weigh these objections. The Paget Prize Plate Co. 

 now supply their plates especially hardened for the 

 tropics if desired, so that they may be developed at 

 a temperature of 90° Fahr. without any danger to the 

 gelatine. Plates should always be dusted carefully 

 before being inserted in the slides and on removing 

 them ; they should not be left in the camera longer than 

 twenty-four hours. Development should be done in the 

 field and as soon as possible, after exposure. I always 

 make a rough proof on P.O. P. paper, so that in case 



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