OK.
So I know now that it was my misunderstanding of the settings of my Camera. I have my solution to that HDR files, separate high and lo iso frames - speed up 2x move one frame and speed up 2x then keying (color luma whatever, mask) and combine that to clips after all doubling frames so the speed is 1x. I end up with film 15 FPS but the dynamic range is high. I will do some experiments with HDR with RAW but the workflow will be a bit more complicated. I'm going to film welding process better then now.
My goal is something like these
https://youtu.be/bwX-NjQHW4c?t=59
So I know now that it was my misunderstanding of the settings of my Camera. I have my solution to that HDR files, separate high and lo iso frames - speed up 2x move one frame and speed up 2x then keying (color luma whatever, mask) and combine that to clips after all doubling frames so the speed is 1x. I end up with film 15 FPS but the dynamic range is high. I will do some experiments with HDR with RAW but the workflow will be a bit more complicated. I'm going to film welding process better then now.
My goal is something like these
https://youtu.be/bwX-NjQHW4c?t=59