Carl Zeiss T ZM Serie Instructions D'emploi page 24

In general, super-wide-angle lenses are known for their
very dynamic perspectives. For this reason, particular care
and exact alignment of the camera are required for image
composition if undesired keystoning is to be avoided. A
tripod can be helpful for architectural pictures. The camera
can be leveled using levels on sale at any camera dealer.
With short focal lengths and initial aperture, edge
brightness in the corners of the images can only be mar-
ginally increased with reasonable technical effort. Slightly
longer exposure often delivers better results in many
pictures. A graduated density filter (image center attenu-
ation 1.5 f-stop) is supplied with the lens for maximum
demands on even illumination over the full frame*.
With this extreme wide angle lens as well, Carl Zeiss has
succeeded in achieving an almost distortion-free image.
However, 3D spherical objects in the image may appear
oval. This effect cannot be avoided even with distortion-
free lenses.
*For the Japanese market the center filter is an optional accessory.
Depth of field table
The following data is based on a circle of confusion
diameter of 0.03 mm.
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