I am having trouble stretching letterboxed footage from a Panasonic DVX100 to anamorphic, i.e 33.33% vertical stretch. I tried After Effects, but the results were disappointing.
I then tried using Photoshop on a still frame from the footage, and the result is spectacular. Obviously, either AfterEffects' stretching algorithm is useless, or I have done something wrong.
Could anyone help me please. What is the best way to stretch footage. I have AfterEffects 5.5 and Final Cut Pro 3

dude,
Turn OFF the mask within the cam when going for anamorphic in Post.

this gives you more room to frame your picture when converting as you have alot more head and botom room to mess with.

I use vegas to do my conversiona dn i have never had any issues.
It could be the image algorithms to "fill the gaps" which could be causeing your issue.

but if u find somehting that works, stick with it.

Vegas' restretching algorithm is extremely high quality. The process works, so I'd suggest that it's your FCP settings that are at the root of your problem; search on FCP forums for recommendations from experts on how to get the best quality resizing.

Thanks for the help guys. Actually I use a Mac so Vegas is not available. I have discovered the render quality settings in AE and all is OK now.

Good. AE's stretch is pretty good as well, though Vegas seems to be the best NLE stretch (certainly much better than Premiere...)

Mike, you saw my reponse to this in the Mac forum, right? It really is the best way if you happen to have letterbox footage. I would recommend working with letterbox bars (unlike Peter) just so you know where your absolute top and bottoms are during the shoot. A fully capable monitor with over/underscan is not always available at the shoot.

"just so you know where your absolute top and bottoms are during the shoot."

I should have mentioned this but it totally slipped my mind.

There are different methods available if the mask is used as a reference for framing,(such as taping or plastic sheet "gels" which u can make) which can simulate the black bars.
Its not the best but it works...
obviously this depend on your method of viewfinding...

I like to use the letterbox in camera for two reasons

I like to use the viewfinder rather than the LCD, and even if I could mask the vf, it wouldn't be as reliably accurate as letterboxing.

Also, I suspect that the black letterbox is "economical" for the compression, and therefore leaves more room for the image. I'm not sure if this is true.