Hi, I shot some HD footage on the Z1, put it on a SD timeline in final cut pro, looks great when burned on to a SD DVD, however i slowed down a few clips in the project and they look really bad, its all jittery, anyone know what to do to stop this? I slowed the clips down by 50%. Cheers.

After Effects can use "pixel motion" when you slow clips down, which kind of blends the frames together in a really smooth way.
In Final Cut there is a "frame blend" check box just below where you chose 50% which is smoother but adds motion trails. When that is off it is incredibly jittery.
The only thing you can do is to either shoot in slow mo to begin with. If you don't have that option just make sure you don't shoot in 24p or lower the shutter speed below 60.

Also, if you shot at 1/30 shutter speed, slowing it down to 50% is going to look very jittery. Make sure to shoot at least at 1/60 if there's a possibility that you'll need to employ slow motion.

Alec Moreno
http://www.1Day1ShotProductions.com

You might also want to check out Twixtor a real cool plugin for FCP / After effects to slow down clips with superb quality

RE:Vision Effects, Inc. : Products: Twixtor (http://www.revisionfx.com/products/twixtor/)

FCP does a very poor job of slow motion, especially with interlaced footage.
As suggested look into Twixtor, or if you have it available use Motion and it's Optical Flow, as it produces great results but is slow.

Oh and in regards to Motion, I find that my render times are much better in FCP, when I render the video clips out of Motion, and take these files back into FCP. Render times are normal this way. but if I export the clips out of Motion and bring that Motion project back into FCP, then the render times get excruciatingly long. SO for workflow, in fCP, send to Motion (as a Motion Project), use Optical Flow for your slow motion in Motion, render your files in Motion, import and replace the clips on the FCP timeline with the rendered Motion clips.