You can use Opacity Envelopes to set many points.

In Vegas 6 you can
Right click the video track and select Insert Envelopes>Insert Composite Level.

I think this used to be called an Opacity Envelope

Hate to tell you buster but you're mistaken.
Opacity levels (BTW, it's still called this in 6.0c) are at the very top of a video event and can be dragged down to less than 100%. That's all you can do though. No keyframing is possible.
Composite envelopes are a separate feature that are accessed as we have both described.

Mike

Thank you very much, this is a nice work around.

It's hardly a workaround! It's meant to work that way by good design.
Using envelopes instead of keyframes gives us a number of advantages.
1) We get a visual cue as to what's happening between nodes.
2) Envelopes are automatable.

The other thing that's not immediately apparent is you can change the compositing mode. By default it's alpha which means the envelope is controlling opacity but one can change this in the track header to other modes such as Add or Multiply. These modes can be very useful not only for interesting effects by controlling the composition of generated media some neat correction tools can be created. Have a long play around, you'll soon discover some very usefull tricks.
Bob.

Mike,

I was replying at the same time you were, so my post is not in response to yours.


Composite Envelopes used to be called Opacity Envelopes in older versions of Vegas. I think it changed over in Vegas 5. I'm not sure if any functionality changed (I think it has to do with parent tracks). So I still think of them in this way.

It's not so much that I'm mistaken, just out of date. Like Grazie.