ioo Photography for the Sportsman Naturalist 



dark room, as they are capable of standing much 

 more light without fogging ; but in flower work, 

 especially, orthochromatic plates are a necessity. 



A ray filter or color screen is a helpful adjunct 

 in use with these plates, as it accentuates the color 

 values. The best consists of simply a piece of 

 glass stained yellow. Any one can make one for 

 himself by thoroughly fixing an unexposed plate 

 in fresh hypo and then, after a short washing, soak 

 it in a ten per cent solution of bichromate of pot- 

 ash until the required density of color is reached. 

 After it has dried, cover the film side with a 

 piece of clean glass, bind the edges, and you will 

 have a perfect color screen. It should be fastened 

 either to the front or back of the lens, and should 

 be so fixed that no rays of light can pass through 

 the lens that do not also pass through the screen ; 

 otherwise it would not answer its purpose of 

 entirely " filtering " the light. It must be remem- 

 bered, however, that, when using one of these 

 screens, the exposure which would be given with- 

 out it must be increased from four to ten times, 

 according to the density of the screen. 



On long trips, where weight and space are a 

 consideration, the cut film is really an excellent 

 substitute for the glass plate and has the added 

 virtue of being absolutely unbreakable. It is made 

 of heavier celluloid than are the roll films, and is 

 carried in a film-holder made for the purpose and 



