blender camera tracker focal length difference

yes, even though this new update might solve all my tracking-problems, i still want to be able to fix this in the old fashion way. also because i do not have the paid version (yet)

After 3d tracking in blender, it all looks great, but when i export an alembic or FBX and import it in fusion, the focal length is always slightly off. I can manually ajust it, but i guess this isnt the ''right'' way to handle and is not always that accurate.

there are tutorials and even a blender-fusion script especially made for this (which doesn't work for some reason) , but i just cant get it right. Also, the camera animation is always 1 frame off but that's an easy fix)

anyone who can help me with this?

Are your film back measurements the same? If the film back is different, then a different focal length is required to get the same angle of view.

Angle of view is always more important than focal length as well. This is why forced perspective works 'in camera': as long as the angles match, then the images will match, whether it's correct or not.

well the focal length seems to be the same. if i change the film back presets to ''regular 35'' it still does not line up correctly. (in blender its set to 35)

i'll try to upload some examples later today

as i am the writer of the blender export script:

what does not work for you with the script? i had some cases where the file path with non standard characters made the comp to not open in fusion.

would like to here from you where it fails and maybe get the comp and blend file