Comment 2 for bug 786035

Thanks Thomas, it now knows about the focal length and crop factor.
I have run a test but not getting very good calibration results.
a=22.9, b=-2.3, c=-11.2, d=-6115.2, and e=105016017.7
Clearly the lines being found are not very good.
The images are of a vertical string line on a brick wall, taken for calibration purposes.
It detects lines in the brickwork,which probably are not too bad. I can't get it to detect the string.
Some more tests needed I think.

Cheers,
Terry