Since most SD is lower field first, and since all HD is upper field first, the Shift Field filter is automatically applied by FCP when you drop SD clips onto an HD timeline. So, it’s most likely correct. If you monitor on a real video monitor, not a computer monitor, you will be able to see the difference in your video when you toggle the filter on and off on a clip.
As far as enhancing VHS blown-up to HD, the only thing that will help is a noise reduction plugin like Neat Video (https://www.neatvideo.com/), and good color correction.
David Roth Weiss
ProMax Systems
Burbank
DRW@ProMax.com
http://www.ProMax.com
Sales | Integration | Support
David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.