User Note No 13: Image Size Changes

F R A Hopgood

24 November 1975

A number of hardware changes made in August have resulted in some changes in the image sizes specified in the earlier User Notes. The correct sizes are given below.

For 16mm and 35mm cine film, the frame area defined in the British Standard is smaller than the abut image with a gap between consecutive frames. The cine image is defined so that on most projectors the outer edges of the image will not be seen. In general, this is preferable to having a blank border around the screen image. However, it may be essential for certain information to be seen. For this reason, a second British Standard image (called cine(projector)) is defined which should be completely visible on all projectors. However, projectors do vary and plotting near the edge of the defined area may not be visible on some.

It is possible to use two different coordinate systems on the FR80, comic and cine. The X coordinate is measured along the film in comic mode and across the film in cine mode. The following tables give the four standard images in both coordinate systems (where applicable).

It is normal to select comic mode on microfiche, and cine mode on other cameras.

On 16mm and 35mm, using the combined camera, 1 raster unit = 0.0000598".

On hardcopy, 1 raster unit = 0.000709".

Abutment is calculated so that boundary lines superimpose.

The cine image has the same aspect ratio as the 16mm cine (projector) image.

The image size is chosen to prevent page overlap. As the aperture plate has rounded corners, the aperture figures given here have been measured across a diameter. A. box with these dimensions will have the corners cut off. No figures are supplied for abutting on microfiche because frames cannot be abutted reliably. This is because the microfiche film is not sprocketed and so cannot be accurately registered.