Anything much beyond doubling is probably pushing it. Of course each image is different. If you plan to zoom in or do panning start with a higher resolution images to avoid pixelation as much as possible. You may get slighlty better results rendering at the best setting. Generally I would not use blur or sharpen, if you must very little. Why? Because if you blur an image you already zoomed in out, chances are you'll just make it appear even worse. Ditto for trying to sharpen.

Instead try sharpening the image in your favorite graphics program BEFORE you bring it into Vegas. Like Photoshop. While there you may want to adjust levels, curves, or do it once you bring it into Vegas.

Wait; are you asking about zooming in on a video picture? If so, you'll find out pretty quickly that a little zooming makes a horrible picture--video is on the ragged edge of acceptability to start with.

If you question instead is how much one can zoom in on a still, then you can go in as far as you want, provided you have the pixels to start with. I have done some pretty deep zooms when working with 1500x2000 stills.

Bear in mind that the finished video frame -- what you actually see on your screen -- is always going to be 720 x 480 pixels in every single frame, no matter how the media that occupies a given frame is manipulated or changed. That means whatever media you want to fill the frame should have AT LEAST 720 x 480 resolution (720 X 528 in square pixel media to ensure undistorted display in DV NTSC playback). As a practical matter, however, you can zoom in slightly on DV resolution media without objectionable pixelization/resolution issues. Heck, I guess you could zoom in even more than usual in Vegas and then use the supersampling feature to upsample it and avoid nasting pixelization, although I've not tried this.

But the best thing to do, presuming you are talking about zooming on stills and will be doing your own scanning, is locate the smallest portion of the image that you want to occupy a full video frame in the zoom/pan move. Measure the width of that portion of the still image in inches. Divide that number by 720, and you will have the scanning resolution (dpi) that you need to scan with in order to get a properly resolved image: one that offers just enough resolution for the zoom but doesn't waste scanning time, diskspace, or RAM in the NLE for resolution that will never be used.

Hope this helps.

Elizabeth Lowrey
Amore Productions

All excellent points (no more than about 2x, higher resolution scan means more zooming). The way you can tell you're at 1x or less is when the "Size" field in the Pan/Crop dialog is 655 or greater. You're at 2x when it's 328, and things will start to get blurry by then.
///d@