Huvitz Excelon EZ Operator's Manual page 30

Excelon EZ Operator's Manual
30
Active Blocking vs Passive Blocking
There are two methods for blocking. Active blocking is to locate the Lens Adapter to
the optical center of the lens. On the other hand, Passive blocking is to locate the
Lens Adapter to the center of the frame which is called 'Boxing center'.
Active blocking is much easier than Passive blocking for blocking. However,
active blocking has several limitations, and also it could make the less qualified
output in special cases. The following table compares active blocking and passive
blocking and summarizes the advantages and disadvantages of them. As it says, if
the optical center is far from the frame center, active blocking could make a little bit
poor qualified output. So, in this case, passive blocking are recommended.
Comparison with active blocking and passtive blocking
Blocking
User
Convenience
There can be additional limitations
Minimum
because of PD, OH(=Optical Height)
Edging Size
B
Edging Quality
of Beveling
Active Blocking
Optical Center of Lens
Just following the Marking Spot of
Lensmeter
l o c k
B l o c k
Eccentric Edging
Block
L e n s
L e n s
Grinding Wheel
Lens
Passive Blocking
Geometrical Center of Frame
Cannot using the Marking
Spot of Lensmeter.
No additional limitation
Centric Edging