When measuring the base curve on an Executive-style bifocal, where should the 3 pins of the clock be placed in relation to the dividing line?

In the context of measuring the base curve on an Executive-style bifocal, placing the three pins of the clock close to the dividing line is essential for achieving an accurate measurement. The dividing line on this type of bifocal is critical because it separates the distance vision from the near vision segment. The base curve ideally should be measured at this dividing line to ensure that the transition between the two segments is smooth and that the optical alignment is correct.

Placing the pins close to the dividing line allows for an accurate representation of how the lens will function in practical use. This positioning ensures that when the lenses are being crafted, the curvature directly impacts how light will pass through at the point where the user will be transitioning from distance to near vision. Ensuring precise measurements at this junction is vital for providing optimal visual comfort and clarity for the wearer.