Where does a person get a "nice" stepper? In an internet search, the nema 17 ones that come up don't seem to have much of a pedigree. My junk box is full of scavenged steppers but I don't know what quality they are. Most are unipolar and I need a bipolar type.
First off, try what you have. It might work perfectly with no added cost.
I'm unsure what the specific requirements are for macro photography but from your comments it seems like the precision of the motion control was very demanding.
Stepper motors can be made cheaply (import) or higher end industrial ones are available. They look the same, however the winding uniformity, magnet strength, etc. is better in the industrial models available. This leads to better torque uniformity, less torque ripple, smoother motion, more accurate step division, etc. Here is a series for Kollmorgan, a well known industrial controls company which acquired Pacific Scientific, known for very high end steppers in the 80's and 90's.
The KM Series of high-torque NEMA 23, 34 and 42 (60, 90 and 110 mm) stepper motors offers a wide range of models to suit most stepper applications. These motors provide an excellent, cost-effective alternative to pneumatic, hydraulic and servo motor systems.
www.kollmorgen.com
For most of us, even the CNC guys, any stepper will do. However, I have worked on industrial projects with work where the motion control requirements were demanding and higher end steppers were selected.
Again, just start with what you have. Good chance it will work well enough.
Can you share any of your photography? I'm curious about it!