Understanding Light and Filters 327
Copying Documents in Polarized Light
A quality copy requires that the plane of the document and the image plane are perfectly
parallel to each other. Align the camera as carefully as possible so that horizontal and verti-
cal lines in the document are perfectly parallel to the edges of the focusing screen. Checked
screens with grids simplify this alignment.
While all Hasselblad lenses have excellent quality at close distances, you may want to
consider the Superwide camera or the Makro-Planars 120 mm or 135 mm in the V system if
necessary, in combination with extension tubes. With the HC Macro 4/120 mm in the H sys-
tem, you can photograph documents as small as 2 in. without close-up accessories.
The Copying Setup
For extensive copying of smaller documents, you may want to consider a special copying
stand. For occasional copying a tripod with the center column reversed so that the camera
sits between the tripod legs, as also suggested for slide duplicating in Chapter 19, makes a
usable arrangement.
Automatic focusing of the H camera should be precise with any type of copy subject. For
manual focusing with V system cameras, place a substitute focusing target — something with
small, very fi ne printing — over a copy subject that lacks fi ne detail. Pre-releasing the camera
or locking up the mirror is a good suggestion on any camera. Filters are usually not needed but
a yellow fi lter can be of value when you photograph old, yellowed originals in black and white
on fi lm or digitally. The fi lter lightens the yellow background thereby increasing the contrast.
Figure 17-9 Polarized light for copying. These illustrations show the improvement when
copying digitally or on fi lm with polarized light and a polarizing fi lter on the lens. (Photos by
Ernst Wildi.)
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