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THE GUIDE TO NATURE 



A NIGHT BLOOMING CEREUS. 



from the object than in life-size work, 

 and the bellows will not need to be 

 extended so far. The depth of focus 

 will increase very rapidly as the dis- 

 tance from camera to the object in- 

 creases. This will overcome the fuzzi- 

 ness of the natural background, and do 

 away with the necessity of an artificial 

 background. The problem to be solved 

 in photographing larger things is the 

 determination of the relative size of 

 the object and the picture. This may 

 be ascertained by the law of similar 

 triangles. Divide the distance from 

 the ground glass to the lens by the 

 distance from the lens to the object, 

 and the fraction will represent com- 

 parative size. Thus, if it is ninety-six 

 inches from the lens to the object, and 

 eight inches from the ground glass to 

 the lens, the image on the ground glass 

 will be one-twelfth as high as the object 

 itself. I do not advocate the taking- of 

 pictures larger than life-size with the 

 ordinary outfit, as it requires a very 

 long bellows, and the depth of focus 

 of the lens is so little that some of the 

 image is likely to be blurred. Besides 

 this, enlarging has become simple, and 

 will produce results just about as good 

 as direct photography. T think the best 



plan, when dealing with small objects,. 

 is to make the negative as large as 

 possible to have every part clear, and 

 then enlarge from that negative to the 

 size desired, either by a Brownie en- 

 larger or a projection instrument, as 

 ( me may prefer. 



The Night Blooming Cereus. 



South Glens Falls, New York.. 

 To the Editor: 



In the December issue of Tiik Guide 

 to Nature I saw a half tone picture 01 

 a single Mower of a night blooming 

 cereus which I consider a rare treat to 

 flower lovers, as I presume all know 

 that these beautiful flowers remain 

 open and live for only a short time after 

 blooming. 



As you published a single (lower, T 

 am enclosing a photograph of a night 

 blooming cereus with three blossoms 

 on it. T took the picture with a rapid 

 rectilinear lens at F. 8 opening and used 

 an Eastman No. 2 flash powder in 

 making the exposure. 



T placed the camera about three and 

 one-half feet from the flowers, and held 

 the flash about three feet from one 

 side of the camera when making the 

 exposure. I developed the negative in 



