Yeah, you can do it, but don't do it in Premiere: do it in AE, where you can use the extra resolution in the HD picture to make a nice animated scale.
Work in an NTSC DV Widescreen AE comp preset and you're all set. I'd also recommend rendering in a lossless codec in AE, then using Adobe Media Encoder to make the mpeg2.
I'm not crazy here right
No, you are.
Create your camera moves in the camera, not in post.
ok now I'm really confused. I tried 2 difference sequences with a 1080i AVCHD source:
#1 1920x1080, keyframed zoomed in from 100% to 215%
#2 720x480 (1.21), keyframed in from 45% to 100%
Exported both to mpeg-2 and h.264, and they're identical? I don't get it. I expected #2 to be vastly superiour quality on the zoomed in portion but it looks just like #1. What am I missing here? I feel dumb.
In Premiere Prefs, deselect the "Scale to Frame Size" option, so that when you Import HD clips into your SD sequence, they remain full sized. You can also do this on a per-clip basis by right-clicking on clip in timeline sequence and choosing from drop down. You will no longer see the entire image, but just a 720x480 piece of the center of the larger HD image, then you are working with the original resolution and can scale as needed and retain the quality of the extra resoution.