512 HANDBOOK OF PHOTOGRAPHY 



of the film, the tinsel being grounded. In this case care should be taken to see that 

 scratches are not produced by this process. 

 4. Remedy. — None. 



Treelike Lines. — (See Static Lines and Markings, above.) 



Blurred Negatives 



In the majority of cases, blurred negatives are the result of improper technique in 

 the focusing or taking of the picture, of excess relative motion between the subject 

 and camera for the shutter speed used, unsteadiness in holding the camera, etc., rather 

 than defects in the negative per se as a result of processing. 



Blurred Negatives. 



1^. Distinguishing Characteristic. — Part of image blurred; objects nearer or farther 

 than main point of interest may be sharp, or not. 



2A. Cause. — (a) Camera not correctly focused or (6) too great an aperture and 

 consequently too small depth of focus for the purpose. 



SA. Prevention. — (a) Proper focusing of camera, making sure that the image of the 

 principal part of the picture is in sharpest focus. With many small hand cameras and 

 especially box cameras no focusing is possible, and in this case proper results can be 

 obtained only with the subject not too close to the camera. With many hand cameras, 

 focusing is accomplished by turning the front element of the lens system or by increas- 

 ing the distance between lens and negative with slide or rack and pinion arrangement. 

 In such cases suitable distance markings are given on the lens mount or on a scale 

 attached to the camera bed, dependence being placed on the judgment of the photog- 

 rapher to estimate distances correctly. For such cases, a distance meter may be 

 useful. If a ground-glass back is provided, still subjects may be focused by means of 

 this back; distances for moving subjects will have to be estimated. Graflex and reflex 

 cameras are usually provided with a focusing arrangement which permits the photog- 

 rapher to view the subject and make focusing adjustments at least up to the time of 

 making the picture. Many high-grade miniature cameras are provided with an optical 

 distance meter which is also coupled to the lens system, so that setting the range finder 

 automatically focuses the camera lens, (b) Insufficient depth of focus may be pre- 

 vented by using a smaller aperture or /-stop or, if perspective considerations permit, 

 this result may be minimized by using a lens of shorter focal length. 



4A. Remedy. — None. 



1J5. Distinguishing Characteristic. — Image completely blurred, although properly 

 focused. 



2B. Cause. — Camera was moved during the exposure. 



SB. Prevention. — Hold camera steady during exposure. If the camera is held in 

 the hands, an exposure of about Ji^ sec. is the longest that many people can make 

 without running the risk of blurring. For exposures longer than this, a tripod support 

 for the camera will be found useful or even necessary. 



4B. Remedy. — None. 



IC. Distinguishing Characteristic. — Background blurred, but image of moving 

 object in foreground reasonably sharp. 



2C. Cause. — In order to obtain sharp image of moving object, camera has been 

 moved to follow it. The background has been sacrificed to obtain sharp image of 

 moving object. Such results are often obtained in photographing fast-moving objects. 



3C Prevention. — This type of blur may be eliminated or at least minimized bj^ 

 (a) photographing the moving object from a greater distance so that the relative 

 motion is less apparent, (b) photographing the subject so as to obtain a more nearly 



