346 



TIIK GUIDE TO NATURE 



always focus through the ray-filter. The 

 thicker the filter, the more the dis- 

 placement. The longer the focus of 

 lens used, the more the shift. In a 

 short focus lens, the stopping down of 

 the lens would probably counteract the 

 slight shift in focus. The longer focus 

 lens, such as the single Protar VII are 

 more seriously affected. 



In photographing a bird's nest with 

 eggs, or the brightly colored eggs to 

 show surface markings, the use of the 

 color-sensitive plates and filter are 

 highly recommended. Assuming your 

 bellows is of sufficient length, this is 

 the procedure when photographing to 

 natural size. Extend the camera until 

 the distance of lens from ground glass 

 is twice what it is when focused on a 

 distant object. Now focus by moving 

 the camera bodily, to and fro, until the 

 image is sharp. The sharp focus will 

 come at the same moment the image 

 size and object size are identical. 



A very easy way is to place a ruler 

 alongside the specimen to be photo- 

 graphed. When the correct focus is 

 obtained the image of the ruler on the 

 ground glass can be verified with the 

 second ruler, and a slight shift in focus 

 made till the size is accurate. It is not 

 at all a bad idea to have the ruler show 

 in the photograph as in this way the 

 size of the specimens are readily shown. 



For perspective reasons, use the 

 longer focus Protar when possible. 

 The proportions of the object are bet- 

 ter preserved and a more pleasing pho- 

 tograph will result. The lens will have 

 to be stopped down more, but this is 

 of small moment as the objects are still. 

 In copying a photograph or a drawing 

 since we have a flat plane, the focus 

 in this case does not matter, and the 

 double Protar should be used. 



In closing it is interesting to note 

 that excellent portraits can be secured 

 with the single combinations of the 

 Protar. The 13^ inch element is 

 almost as long in focus as the regular 

 portrait lens of the photographer, and 

 the perspective is therefore of the same 

 degree of excellence. 



cal Company, Rochester, New York, 

 and listed as Vila for the convertible. 

 These lenses are mafic in Germany 

 at The Zeiss Works, and sold in this 

 country by E. B. Meyrowitz, New 

 York City, and called double Protars. 

 Both makes are faultless and of highest 

 optical excellence. Much of the best 

 photographic work in this magazine 

 has been done with Protars — E. F. B.] 



[Note — Protar lenses are made in 

 America by The Bausch & Lomb Opti- 



Roses Hidden by Thorns. 



To one who loves lenses there is no 

 more interesting reading than the tabu- 

 lated schedules — those formidable, 

 thorny features of a photographic lens 

 catalogue. I often think that such 

 pages must be repellent to those who 

 know nothing of lenses, but one needs 

 only to push the thorns aside to reach 

 the inward beauty of these wonderful 

 specimens of workmanship, and to give 

 life to focal lengths, apertures, "U. S." 

 and other mysterious emblems and 

 titles. 



How like nature itself is the photo- 

 graphic lens catalogue ! Some people 

 pass by the most interesting objects 

 and see nothing of charm or of interest. 



As I was recently showing through 

 Arcadia a party of girls who spent their 

 week days in a factory, they frequently 

 exclaimed, "Why! they pick up and 

 seem to like any old thing that you or 

 I wouldn't even notice." What a piti- 

 ful comment upon themselves is this 

 thought in a world of wonderful, re- 

 sourceful interests and beauty. Why 

 are their eyes so blinded? 



But pardon the momentary reversion 

 and bit of soliloquy, and let us go back 

 to the lens catalogue. What a pity it 

 is that so many camera users, even 

 those with plenty of money to spend on 

 anything that will afford them pleas- 

 ure, throw aside the lens catalogue as 

 disagreeable propositions and masses 

 of unintelligible data. 



Not a Aery long time ago, a friend 

 who has used a hand camera for years, 

 said to me, "It never occurred to me 

 that those lenses are for me to use. 

 I thought the anastigmat and all oth- 

 ers described in that Choctaw language 

 were aimed wholly at the professional." 



