412 



Sierra Club Bulletin 



a point at least an inch nearer the lens. This allowance will in- 

 sure that the animal itself rather than the tree trunk is sharply 

 in focus. By placing the camera three or four feet distant an 

 image nearly one inch high will be obtained with a seven-inch 

 lens. Beware of attempting to work too close to the subject. 

 It is better to enlarge an inch image later on than to try to se- 

 cure a large image at once by working close up. By working 

 at a reasonable distance, depth of field is obtained and the 

 animal is not badly frightened. A long-focus lens can be used 

 to advantage ; but the use of the single combination of the or- 

 dinary lens was found to be too slow for such active animals 

 as chipmunks. 



Exposures of 1/50 second at stop 11, or 1/25 second at stop 

 16, were found to give well-exposed negatives when the sub- 

 jects were in direct sunlight. The shorter exposure was found 

 best, and even then the motion of the front feet or paws was 

 not always stopped, as is seen in the photograph of the Alpine 

 Chipmunk. Exact data for this picture (plate ccxxiii) are as 

 follows: September i, 3 p.m.; bright sun; 10x15 cm.GoerzTen- 

 nax camera; 65^-inch Dagor: stop f/ii ; 1/50 second; lox 15 

 cm. Cramer Inst. Iso. plate; pyro in tank; enlargment 3^ 

 times on No. 6 Studio Enlarging Cyko. It will soon be 

 found that momentary pauses in the animals' activities can be 

 taken advantage of and good negatives secured at these op- 

 portune moments. 



All moving parts (levers) of the shutter should be hidden 

 from the chipmunk's keen vision. Otherwise, the animal is 

 warned of danger when the release moves and starts to flee 

 before the exposure is complete, a blurred negative resulting. 

 By draping a piece of cloth over the releasing lever this ten- 

 dency of the sitter to "jump the gun" is avoided, and sharp 

 negatives can be secured. A black pasteboard box set on the 

 tripod was found to serve excellently as a dummy to accustom 

 the animal to the camera. The shutter was usually operated at 

 a distance of about fifty feet, by means of a thread tied to the 

 shutter release. By this method one is able to watch the sub- 

 ject from a distance and still make the exposure at the proper 

 time. 



It should be remembered that the co-operation of the animal 



