DEFECTS IN NEGATIVES AND PRINTS 513 



"head on" view, (c) using a shorter exposure so as better to arrest the relative motion. 

 In the latter case a larger aperture or a faster emulsion may be required to obtain the 

 proper exposure with the shorter shutter speed. 



4C Remedy. — None. 



ID. Distinguishing Characteristic. — Some planes of the image in sharp focus; other 

 planes out of focus. 



2D. Cause. — Insufficient depth of focus. 



3D. Prevention.— De^pih. of focus may be increased by using a smaller aperture 

 in taking the picture. For a given aperture, greater depth of focus will be obtained 

 with a lens of short focal length rather than one of long focal length, but perspective 

 considerations must be taken into account in selecting a lens of proper focal length. 



4D. Remedy. — None. 



\E. Distinguishing Characteristic. — Image generally indistinct. 



2E. Cause. — A negative lacking in sparkle, snap, or contrast may be due to (a) a 

 dirty lens in the camera, (6) flat lighting or lack of contrast in the original subject, (c) 

 insufficient contrast due to insufficient development, or {d), although relatively rare, 

 fog or moisture condensing on the lens of the camera. This latter condition is espe- 

 cially prevalent if the lens is suddenly removed from a cold dry atmosphere to a warm 

 moist atmosphere, in which case moisture condenses on the lens until the lens reaches 

 temperature equilibrium with its surroundings. 



^E. Prevention. — (a) Cleanliness is the only answer here. The lens should be 

 kept clean. Dust should be removed with a camel's-hair brush. A dirty lens may be 

 cleaned with soft lens tissue, after the lens has been breathed upon so as to condense 

 moisture upon it. Water, alcohol, or other liquids should not be used, nor should linty 

 or coarse cloth be used in wiping the lens. (6) Flat lighting or lack of contrast in the 

 original subject often cannot be prevented, especially when making outdoor pictures 

 on cloudy days, (c) Contrast can be increased (up to its limiting value) only by 

 proper exposure and development. Contrast depends upon the exposure range, but 

 for flat subjects with little contrast the apparent contrast may be increased by fairly 

 long development of the negative and then printing on a contrasty grade of paper. 

 (d) Do not subject the lens to sudden changes in temperature or humidity. If this 

 cannot be avoided, allow the lens to reach equilibrium conditions with its surrounding 

 atmosphere before making exposures. 



AE. Remedy. — Printing a flat negative on a contrasty grade of printing paper is 

 perhaps the best remedy for improving contrast. No remedy for other causes. 



IF. Distinguishing Characteristic. — Parts of film out of focus or indistinct, with 

 remainder of film satisfactorily sharp. Sometimes the images may also be somewhat 

 wavy. 



2F. Cause. — Film was buckled in film holder during exposure; not perfectly flat. 



3F. Prevention. — Maintaining the film at uniform temperature, allowing film to 

 reach equilibrium temperature with its surroundings before taking picture if it has 

 been subjected to sudden temperature changes, and loading the film in its holder just 

 prior to exposure are useful in minimizing this type of defect. Buckling of film occurs 

 much more frequently with large than with small negatives. The film holders should 

 be inspected to see that they hold the film properly flat. In extreme cases, it maj^ be 

 necessary to use plates rather than film. 



4F. Remedy. — None, although retouching may be used in many cases to counteract 

 the undesired fuzziness due to buckling. 



Multiple Images. 



1. Distinguishing Characteristic. — Multiple images appearing superimposed on the 

 same negative. 



