PLZ figure out what stepper motor I should buy

I am currently building a 3D scanner turntable and I can’t figure out what stepper motor I should buy.

Here are some things to consider:

The plate will be made out of 3/4" MDF and will be 2’ wide (diameter);
The plate’s weight will be supported by a ball bearings system (just like a lazy susan);
I need to support objects with a weight up to 5 pounds;
The motor’s shaft will be placed directly in the middle of the plate (no gears system, for maximum precision and simplicity);
I need a motor accurate enough to be able to calculate/simulate camera angle;
The turntable will turn at a very slow RPM (1 RPM or less);
I will be programming everything in a C/C++ program.
Here are my questions:

NEMA-17 or NEMA-23 (and why)?
What controller would I need? How can I communicate with the motor from a C/C++ program (Arduino or not)?
I was considering these:


Arduino UNO with Adafruit Motorshield V2
A NEMA-17 stepper motor with a 0.9° step angle

Phidgets controller (still a little too pricy for me):
Phidgets stepper motor:

The basic mechanics of the BQ Cyclops design should meet your needs. I was never able to get one to work right, but that was probably more down to camera and software than mechanicals or the controller board. That one uses a NEMA 17 motor. A NEMA 23 is going to be overkill unless you are building a massive turntable.