I’ve struggled to master Advanced Camera Tools for a while and seem to have exhausted the help pages to learn any more, but as I’ve been experimenting, I may have a clue about this. The short answer is to have two scenes from the exact same viewpoint, but one is an ACT scene and one isn’t, but SU is messing up with focal length.
I reported in another thread here, that I believe under normal operation, what SketchUp reports as focal length is actually wrong. It’s off by a factor of 1.5x, at least if it’s assuming a standard 35mm still camera. Things with the camera work differently under ACT and Match Photo than normal operation. When you make an ACT camera, what it reports is the correct focal length. This test file here is still a work in progress. All of this is based on a 35mm still camera or full frame digital equivalent:
This is native tools and vertical angle of view set correctly for 24mm lens (SU will report this as 36mm)
When you create an ACT camera, it then sets the focal length to 36mm (actual).
This is ACT after resetting the focal length to 24mm.
If you don’t change any parameters and simply create a new scene (not duplicate), SU uses an angle of view for what it calls “24mm”, but actually corresponds to 16mm.
If you use the Zoom tool and set the angle of view to 51.3* or what SU calls “36mm” you get back to the same view.
So, is this not a bug?