For me it would be convenient, if the render output size, in preferences, could not be specified in percentage, but in pixels (wide).
You can enter the size (width) in pixels in the topmost leftmost field of the Render window ...provided it's not larger than the computed "100%" width (see screen capture) but you can't specify that in global preferences.
Perhaps you have a different formula to calculate the Fov. And therefore the differences.
It would be very interesting how you calculated the Fov.
Computed FOV depends on:
- FOV values as computed by the optimizer
for each source images
- yaw values computed by the optimizer
for the leftmost and for the rightmost source images
- number of pixels per angular unit at the image center (wich depends on actual
focal length, distance settings
, pixel width of the sensor and actual sensor size)
- selected projection mode
- image crop (automatic or manual)
A difference between the FOV you compute and the FOV autopano computes is unavoidable but it should not be very large...