SAMPLE PLOTS IN SILVICULTURAL RESEARCH 55 



research agency support cameras that do not take photographs 

 larger than 19 square inches. A tripod should always be used. To 

 get an identical view in a repeat picture, it is necessary to use a 

 camera of the same size and with the same focal length as the one 

 previously used and to orient the photograph by a print of the 

 one preceding it. 



Photographs in the woods are best taken on cloudy, windless days, 

 when the contrast between light and shadow is not great and there 

 is no movement to blur long-time exposures. For a picture of a 

 stand, since depth of focus is desirable, small stops with correspond- 

 ingly long exposures should be the rule. A photometer aids greatly 

 in properly timing pictures. For the best results, color-sensitive 

 films and color screens should be used. Where the sky shows through 

 the crowns, the use of a graduated sky filter is recommended. Pre- 

 cautions should be taken in handling and developing special films 

 to avoid fogging. 



Overexposure is preferable to underexposure. An overexposed 

 negative can often be saved by reduction, but no treatment can 

 intensify details that are not present in the negative. 



A record should be made of each picture when it is taken. This 

 record should show photograph number, date and hour, stop and 

 exposure used, light conditions, position of camera, direction of 

 view, kind and focal length of lens, kind of filter, and type of film, 

 and should include a description of the camera. (It is suggested 

 that the lens number be noted.) These items should be followed by 

 a complete description of the view, and an explanation of its choice. 



A view can be permanently identified as to location by including 

 in it the plot number and station designation. For this purpose, 

 use may be made of a series of large loose-leaf numbers and letters 

 that can be combined in any desired way. 



Some object that will give an idea of relative dimensions should 

 be included in each photograph. 



Repeat pictures should be taken at all the permanent camera sta- 

 tions at the time of remeasurement, even if no readily apparent 

 change has taken place in the view. Lack of change may be highly 

 significant in some cases, and something significant may be brought 

 to attention by the photograph or may show up at the time of the 

 next visit. If a picture is not repeated, the reason should be noted. 

 Even if one photograph has been a failure, the fact that plots are 

 presumably to be under observation for a long time justifies making 

 a photograph from the same point at each later visit. 



Retakes offer a better opportunity for comparison if always taken 

 at approximately the same time of year and of day. Otherwise, 

 minor vegetation of importance from the project standpoint and 

 visible in one photograph may be obscured by snow in a later one. 

 In the case of hardwoods, the whole aspect may be changed by the 

 presence or absence of foliage. Uniformity as to time of day results 

 in similarity of light and shadow effects. 



