The video camera’s lens axis should ideally be aligned with the horizontal and vertical centreline of the film frame in the film gate. I made the assumption that the ¼ inch Whitworth tripod mounting hole on the video camera was on the vertical centreline of the lens axis. To establish accurately the height of the horizontal axis of the lens above the camera base I captured a still image with the camera of a steel rule held vertically. I then opened the image in Xnview selected View > Display colour information to show the pixel information at the eyedropper cursor and read the rule at the pixel row at the centre of the image 37.9 mm above camera base e.g., image height = 1536 pixels so centre row is = 768.
Beware my Canon HV 20 video camera takes 2048 x 1536 pixel still frame images. The video camera’s centre line height plus the height of the camera platform should equal the centre line height of the film gate above the common base board datum.
I used the program Xnview to capture the cursor information shown in Photograph 18 .