If you render to another .avi, you may not notice a thing. Every other format you render to is definitely some kind of loss, but you still may not notice a thing (some mpeg2 is pretty good, while WMV and other downloadable formats are very noticeable). If you render to a no compression format (uncompressed DV), there should be no change, but you probably don't have a big enough hard drive for that one.
Edit: Spot answered as I was typing this, so listen to him over me. He's the expert.

To Spot:

You write in your book on Vegas (p. 404): “If files are exported from Vegas using the standard NTSC-DV settings, most third-party applications can read the files, but until Sony opens their codec up to other applications to use, those third-party applications can’t write back to the Sony codec. Therefore, an uncompressed codec is the answer.”

Two / three questions to Spot and everyone else:

1. What is your opinion regarding the quality of the MainConsept DV codec compared to Sony’s DV codec?

2. If I have to export video from Vegas, for example because I want to stabilize the footage in another application (Adobe Premiere Elements) or correct colours (Pinnacle Liquid), should I export using the Sony DV codec, or should I use the MainConcept DV coded? I use the MainConsept DV codec when re-exporting the footage after stabilizing.

3. Or formulated in more general terms: should I use the same DV codec (MainConsept) when transferring (exporting and importing) video between different applications? Or should I use the native DV codec used by each application (Vegas, Adobe, and Pinnacle)?

Joran, Norway

I'll defer to Spot, but in my experience the Sony DV codec is pretty close to perfect. The MainConcept DV codec is good, but not as good. Therefore, whenever you can, use the Sony DV codec.

IMO, the only two GREAT DV codecs are the Sony Vegas and the Canopus. Main Concept would come next, with a host of others following behind. Even Microsoft has gotten "reasonable" but stick with the Sony codec, you'll be happiest, I think.
Try a render test using colorbars and pluges. You'll likely be surprised at how well Vegas holds up vs the other guys.

John

I'm a little confused....Are you saying there is a Sony alternate to the Main Concept MPEG2? I don't see a Sony type in that selection box except for audio.... Which Sony codec are you guys talking about? Are you talking about the template ie:DVDA NTSC Video Stream or am I out in left field with no glove?

Keith

[Edit] OK I was typing while Douglas was.....where is this Sony codec?

I think they were referring to the MainConcept DV codec. The Sony DV codec is buried in Vegas and can't be used by any other PC programs, to my knowledge.

Previous tests have shown that the Sony (Sonic Foundry) DV codec can survive dozens of encode/decode cycles without any artifacts.

Two questions concerning the Canopus DV codec:

1. Can we export video from other programs, like TMPGEnc 3.0 Xpress, using the Canopus DV codec – in the same way this is possible using the MainConsept DV codec?

2. I visited the Canoupus homepage, but I could not find the DV codec mentioned by Spot. Where can I buy it, and what is the cost?

Joran, Norway