How to calculate precise vertical and horizontal field of view of camera in photo and video mode in SDK 4, if it returns only 35mm equivalent focal length, but no matrix size or its original aspect ratio or at least its maximal resolution to calculate aspect ration?

To be able to calculate FoV we need one of this options:
1) Real matrix size in mm to calculate crop factor and then real focal length and then arctan for angles from real width or height and real focal length.
2) Original aspect ratio to calculate equivalent 35 mm matrix size with the same diagonal and then use its dimension in original aspect ration and 35 mm focal length.
3) Maximal resolution to calculate original aspect ratio and do the same way as in p.2

But DJI SDK has nothing except 35 mm equivalent focal length and currently selected aspect ratio which may not be equal to original.

Could somebody explain how to calculate precise vertical and horizontal FoV?

How to calculate precise vertical and horizontal field of view of camera in photo and video mode in SDK 4, if it returns only 35mm equivalent focal length, but no matrix size or its original aspect ratio or at least its maximal resolution to calculate aspect ration?

To be able to calculate FoV we need one of this options:
1) Real matrix size in mm to calculate crop factor and then real focal length and then arctan for angles from real width or height and real focal length.
2) Original aspect ratio to calculate equivalent 35 mm matrix size with the same diagonal and then use its dimension in original aspect ration and 35 mm focal length.
3) Maximal resolution to calculate original aspect ratio and do the same way as in p.2

But DJI SDK has nothing except 35 mm equivalent focal length and currently selected aspect ratio which may not be equal to original.

Could somebody explain how to calculate precise vertical and horizontal FoV?