12-10-2010, 03:35 PM
[quote name='popo' timestamp='1291967728' post='4918']
Who/where does it say faster than USM? I wonder how it compares to their own USD.[/quote]
Yup, Tamron did NOT claim it'll be faster than USM. The advantage of PZD motors is reduction in size compared to USM.
From Tamron:
"Ultrasonic motors are divided into two categories depending on the principle that generates the energy to move the drive: traveling wave motors and standing wave motors. Traveling wave motors include the ring-type ultrasonic motor used in the recently launched SP 70-300mm VC USD as well as other lenses, but this lens employs a newer technology, the PZD (Piezo Drive), which functions on the standing wave principle.
A standing wave ultrasonic motor utilizes high-frequency voltage to extend and turn the Piezoelectric (Piezoceramic) element, thus moving the entire element in a standing wave movement. The metal tip is the contact point of the element to the rotor, and moves in an elliptic motion from the swiveling motion of the moving element, and the friction from this motion turns the rotor. Standing wave ultrasonic motors have the distinct advantage of being smaller than their traveling wave counterparts, and therefore allow a more compact SLR lens size."
Elsewhere, Tamron states:
"PZD (Piezo Drive) is a standing wave ultrasonic motor system developed by Tamron. The motor is faster and quieter than DC motors when the AF drive is operated, and compared with ring-type ultrasonic motors, it has an actuator that facilitates lens design and reduced size."
So faster than standard DC motors and smaller than ring USM.
Who/where does it say faster than USM? I wonder how it compares to their own USD.[/quote]
Yup, Tamron did NOT claim it'll be faster than USM. The advantage of PZD motors is reduction in size compared to USM.
From Tamron:
"Ultrasonic motors are divided into two categories depending on the principle that generates the energy to move the drive: traveling wave motors and standing wave motors. Traveling wave motors include the ring-type ultrasonic motor used in the recently launched SP 70-300mm VC USD as well as other lenses, but this lens employs a newer technology, the PZD (Piezo Drive), which functions on the standing wave principle.
A standing wave ultrasonic motor utilizes high-frequency voltage to extend and turn the Piezoelectric (Piezoceramic) element, thus moving the entire element in a standing wave movement. The metal tip is the contact point of the element to the rotor, and moves in an elliptic motion from the swiveling motion of the moving element, and the friction from this motion turns the rotor. Standing wave ultrasonic motors have the distinct advantage of being smaller than their traveling wave counterparts, and therefore allow a more compact SLR lens size."
Elsewhere, Tamron states:
"PZD (Piezo Drive) is a standing wave ultrasonic motor system developed by Tamron. The motor is faster and quieter than DC motors when the AF drive is operated, and compared with ring-type ultrasonic motors, it has an actuator that facilitates lens design and reduced size."
So faster than standard DC motors and smaller than ring USM.