Pixel size + focal length entered in calibration step calculator causes confusion

A user reports that entering pixel size in the calibration step calculator does 
not persist across sessions. This is the case because entering the value in the 
cal step dialog is not updating the "real" camera pixel size (from the camera 
tab of the brain and used throughout the code).

The design currently provides two places for the user to enter pixel size and 
focal length (config pages in brain vs cal step dialog), so it is 
understandable that a user would not know which is the "real" setting or 
overlook the "real" setting.

I can think of a few ways to resolve the confusion:
  1. make the fields in the cal step dialog read-only, with tool tip hints directing the user where to go to enter the values
  2. have the cal step dialog update the "real" values (as if the user had updated them on the corresponding tabs of the brain); do not update the values if the user hits the Cancel button.
  3. remove the values from the dialog. Use the "real" values internally for the calculation, but do not display them. Display an error if either of the values are missing, or, better, disable the "Calculate..." button until they enter them (but provide a good tool-tip hint so they know why the button is disabled).

I think #2 would be best. I'd be ok with #3 too.

Original issue reported on code.google.com by andy.gal...@gmail.com on 30 Dec 2013 at 8:07

DanielVanNoord / open-phd-guiding

Pixel size + focal length entered in calibration step calculator causes confusion #234