PHOTOGRAPHING TREES, ETC. 119 



or ray-filter that the beginner usually fails. He 

 uses it when it is unnecessary and neglects to use it 

 where it should be used. In photographing a blue 

 flower with even fairly dark leaves, the ordinary plate, 

 being highly sensitive to the blue and very slightly 

 sensitive to the green, does not give the colour values 

 correctly : the blue is too light and the green too dark. 

 The colour-screen or ray-filter will correct this. 

 The common fault is in using the deep-coloured screen 

 when photographing a red or orange flower. The 

 ordinary plate, being only slightly sensitive to the red, 

 orange, and green, requires a longer exposure than 

 when other colours predominate, but gives the values 

 of these colours fairly accurately; the deep-coloured 

 ray-filter only tends to increase the exposure neces- 

 sary. For most flower-work the medium isochro- 

 matic plate is the most satisfactory. If the flower is 

 very shaky the quickest plates are best, and if white 

 flowers with dark green leaves are to be rendered 

 accurately, then use the slow plate or the ray-filter; 

 this will hold back the white and give the green 

 better value. 



When photographing very delicate flowers, it is a 

 good plan to place around them a screen of white or 

 light-coloured cloth that will protect them from the 

 wind and at the same time" reflect more light. This 

 cloth should be stretched tightly on upright sticks, 

 which should be firmly planted in the ground, not 



