All Parker's stepper motors are built with 50 pole pairs, resulting in 200 physical steps per revolution. But by using Parker's microstepping technology (included on all stepper drives), you can actually get 25000 steps or more per rev. The maximum number of steps/rev really depends on the drive.
Gemini (GT/GT6/GT6K): 128000
Vix IM: 51200
Zeta / OEMZL: 50800
E-AC / E-DC: 50800
OEM750/750X: 50800
OEM650/650X: 50800 (also applies to the OEM350/350X)
S/SX: 50800
Integral E: 36000
PDS/PDX: 4000
What effect does resolution have?
When the drive receives step pulses from its indexer (a.k.a. controller), it turns the motor that many steps. However, the size of each "step" is decided by the drive's Resolution setting.
Higher resolutions mean that the drive will make the motor take smaller steps. So, if two drives receive the same number of steps from an indexer, the drive with the higher resolution will spin its motor slower, and not as far, as the drive with the smaller resolution.
The higher the resolution, the more precisely the indexer can position the motor. With a resolution of 50,000 steps/rev, the motor can be positioned at any one of 50,000 different places! This is equivalent to 0.0072 degrees.
Full-stepping is when the drive turns the motor one full physical step (1/200 of a revolution) per indexer step that it receives. Half-stepping means each step is half as big, so the motor will need twice as many steps to go 1 revolution.
With microstepping, we can control the motor with much greater precision, making it take extremely tiny steps. Microstepping a motor also improves smoothness and greatly helps to reduce resonance. There is a slight reduction in torque as compared with full-stepping.
No matter what resolution a drive is set to, the smallest increment the motor can actually turn, from start to finish, is about 0.1 degrees. (This is the amount necessary to overcome friction.) Of course, you can turn the motor forward 0.5 degrees, and then backward 0.495 degrees!