Composite size not the same as editor when animating size
I am using HitFilm Pro 13. I have set Full HD video, i.e. 1920 x 1080, for my Project settings and the video is also FHD.
I have a video clip whereby I exported the 1st frame so I can make a composite shot from it to "fake" a camera zoom out and make it look like it belongs to the clip, i.e. the 1st frame is zoomed in and the last frame is the same size as the 1st frame of the clip it came from.
When I place the composite shot without any changes to it in front of the clip and play it, the picture stays nice and still and the same size as the 1st frame of the video clip. As soon as I change the size of the composite to 130% at key frame 1 and return to 100% at the last or even 5 key frame before the end of the composite shot and play the sequence back, the last frame(s) of the composite shot are much larger than the 1st frame of the clip it came from. To make it look the same size, I have to reduce the zoom to 84%, not 100%.
The project settings, the video clip and the still taken from it are all set to FHD.
Where am I going wrong? Why is the composite shot not the same size at 100% as that of the video clip?