Cinematography-Theory-And-Practice

Figure 14.15. A split diopter givesfocus both on the near objects(cards) and the far object (actor).Notice the fuzzy transition line,which is fairly well concealed here.Exposure Compensation in MacrophotographyWhen a small image is being “spread” over a large piece of film, itnaturally produces less exposure. With reproduction ratio’s ofgreater than 1:10, exposure compensation is necessary. The formulafor this is:f/stop determined by meterShooting f/stop = 1 + magnification ratioExample: meter reading is f/8. Your reproduction ratio is 1:2 or1/2 size. The calculation is 8/(1 + .5) = 5.3Depth-of-Field in Close-Up WorkThere are many misconceptions associated with macrophotography;perhaps the most basic is that “wide-angle lenses have more depthof-field.”Depth-of-field is a function of image size, not focal length.While it is true that wide-angle lenses have more depth-of-field, theproblem is that once you have put a wider lens on, you still want thesame image you had before, and in order to accomplish that, youmust move the camera closer to the subject. Once you have done this,the depth-of-field is the same as it was before, since focus distanceis also an determinant of depth-of-field. The important aspects are:Calculating Depth-of-Field in Extreme Close-Up WorkCalculation of depth-of-field in extreme close-up work methodsis different from normal situations. At magnifications greater than1:10, the depth-of-field is extremely small and it is easier to calculatethe total depth-of-field rather than a near and far limit of the zoneof focus. Total depth-of-field is calculated by the following formula:2C x N (1 + M)Dt =m 2Dt = total depth-of-fieldC = circle of confusioncinematography282