User`s manual

Biaxial Displacement Follower User’s Manual Version 1.4, April 19, 2004 IM1013

Page

Figure 6 shows that the equivalent 105mm lens cannot be considered to be located exactly at the end of the extension tube.

Its equivalent position is, in fact, approximately 13mm further along the optical axis than the position used in the

calculations. This positioning of the lens in its diaphragm varies with different manufacturers and no one rule will solve the

problem.

It is best simply to estimate where the plane of the lens might be located on the lens holder and measure the distance from

that point to the point of attachment of the lens holder to any extension barrels used. This distance should now be included

in the length calculated for the extension barrel. Applying this to the example above, the actual barrel length to be used

would be (86.4mm-13mm) or approximately 73mm.

Working distances and full-scale measurement ranges have been calculated for the 105mm and the 50mm variable-focus

lenses. For convenience, these values have been put into a table on the Standard Lens Sheet on page 22 .

Note

Since the values in the table are obtained by experiment, not from theoretical calculations, they are more realistic for

actual set-up than calculated values would be.