514 HANDBOOK OF PHOTOGRAPHY 



2. Cause. — Exposure of the same film more than once. 



3. Prevention.— Cevlava. modern miniature cameras cannot be operated until the 

 roll film has been wound so as to have a new frame in place. Thus, double exposure 

 is automatically prevented. For other roll-film cameras, turn the roll film until a 

 new (unexposed) portion of the film is in place immediately after each exposure. For 

 film-pack cameras, pull the exposed negative after each exposure to the back of the 

 pack with the paper tab provided for that purpose. For plate cameras, remove 

 exposed plates from the cameras immediately after exposure, and mark the holders to 

 indicate plate has been exposed. 



4. Remedy. — None. 



Distorted Images on Negatives 



Distorted images on negatives, like blurred negatives, are to be regarded more 

 correctlj^, as a general rule, as being due to defects in the manufacture, application, or 

 use of the optical system of the camera rather than negative defects per se. The 

 discussion of distorted images included here is intended as an aid to the photographer 

 in perfecting his technique and in locating possible trouble in or improper use of his 

 equipment. 



Distortion Due to Buckling of Negative. 



1. Distinguishing Characteristic. — Part of negative out of focus and fuzzy, although 

 remainder of negative may be quite satisfactory. 



2. Cause. — Buckling of film in the plateholder before or during exposure. 



3. Prevention. — Care in inserting film in film holder and making sure that the film 

 is held perfectly flat; inserting film in camera just prior to exposure; maintaining film 

 at constant temperature and humiditj^ are effective aids in minimizing buckling. 

 Buckling is greater with large film than with small films. In extreme cases, plates 

 rather than films may be required. 



4. Remedy. — None, aside from retouching negative. 



Distortions Due to Camera Adjustments. 



1. Distinguishing Characteristic. — There are several possible distinguishing charac- 

 teristics for distortions due to camera adjustments or misadjustments. The most 

 common and most important of these include: (o) too much of subject included in the 

 picture; (6) insufficient amount of subject included in the picture with, perhaps, part 

 of desired subject not included; (c) improper perspective; {d) vertical lines converging; 

 (e) too much or too little foreground included; (/) slight lateral distortion. 



2. Cause. — Generally the defects mentioned above are caused by improperly using 

 the camera adjustments, or may result because the camera is not provided with adjust- 

 ments, which are required for the type of work being undertaken and which would 

 enable the photographer to prevent these distortions. More specifically, the causes 

 may be given, respectively, as follows: (a) If the perspective is satisfactorj^ but the 

 image is too small, the difficulty was that the camera was too far removed from the 

 desired subject. If the perspective is bad, this may mean that a lens of too short focal 

 length or too wide an angle of view was used. Bad perspective may also be due to 

 viewing the picture from incorrect distance, when either a contact print or an enlarge- 

 ment is made, (fe) This defect may be the reverse of (a) or may be due to improperly 

 aiming the camera at the desired subject. If the image is of proper perspective and 

 size but the subject is not entirely included in the picture, faulty aiming of the camera 

 is indicated. While such results can always be avoided with view cameras, cameras 

 provided with precise view finders corrected for parallax, and single-lens reflex cameras, 

 results of the type mentioned are not infrequently encountered with less expensive 



