Navitar Motorized Zoom Systems Instruction Manual for Windows
Revision B
Page 13 of 23
2/17/2004
8.6.1.2 Customer Setup - Max Velocity
This value specifies the maximum velocity, in steps per seconds, which the motor
may attain after ramp-up in accordance with the desired acceleration curve.
8.6.1.3 Customer Setup – Acceleration
This value relates to the time it takes to go from the initial velocity to the
maximum velocity (ramp up). Generally, the heavier the load on the motor, the
smaller the number should be. If the acceleration is set too high, the motor may
stall during the acceleration. If the number is too low, the motor will take longer
to reach its destination.
8.6.1.4 Repeatability / Backlash Elimination
Most geared systems have “backlash”, (the inability of output to instantaneously
track input). The motorized zoom picks up play from the motor’s internal gearing,
zoom drive gears, and cam clearances. There are means (expensive) of
reducing (but not totally eliminating) this.
To be able to repeat a zoom setting accurately, Navitar software contains an
option that forces all motion to work against gravity, thereby effectively
eliminating the backlash. (There is no other positive means to guarantee
repeatability in this kind of a system). With this option, any time the command is
to travel to a lower zoom setting, the zoom goes back to the home position,
resets to 0, and then approaches the end point traveling up against gravity.
The above requires that the “zero” be set at “near” (bottom of the zoom travel),
and that the “down thru home” button be activated. Also, due to “coasting”, a
position reached in one step will differ from that reached in multiple upward steps
totaling the same number.
Recommended Initial Values
AXIS 1
AXIS 2
2ø
8000
2000
5ø
2000
6000
DC Encoded
N/A
N/A
Recommended Initial Values
AXIS 1
AXIS 2
2ø
10
10
5ø
10
10
DC Encoded
N/A
N/A
