Focal length in Agisoft Lens calibration

[Chukopter]

Hi,
I am curently trying to calibrate my cameras I am using in a Photoscan project externally in Agisoft Lens.
A couple of questions appeared: The EXIF-data says my focal length is 3, while the manufacturer states that it is 2.97. Unfortunatly, you can't change the initial parameters in Lens, right?
Secondly, I don't understand why the software recalculates this value, which seemed quite fixed to me, reporting a true focal length of 2190 (um?) in the calibration file.
In the camera calibration step in Photoscan I can then load the calibration file, but also put in my original value in the field above!?

3. Phothoscan doesn't seem to bother about parameters P3, P4 and K4. Should i let Lens also calculate these, or keep them unchecked?

Cheers,
Frederic

[nickmac]

My experience has been that Photoscan is extremely good at working out the accurate focal length when it does the alignment of photos so making sure the exact value is in the focal length field isn't very important.

If you were using a 3mm lens then you will need to make sure you set the camera type to fisheye in the Camera Calibration settings.

I have gotten good results from leaving the other values blank and letting Photoscan work things out. Depending on the workflow you are using you will want to export undistorted photos from Photoscan once you have created the camera alignment.