Forgive me if this has been asked before, but I did a search of the forum and couldn't find anything.

What is the best file format to render D800 files to? I'm using Vegas Pro 11 and would like to get the best quality from the rendered file.

Matt, it all depends on what the final use will be.
For example, an SD DVD requires a different format than a Blu-ray or a YouTube/Vimeo render.
Be more specific and you'll get several recommendations.

AVI UNCOMPRESSED - is the absolute best format.. No compression at all, it renders the file to an .AVI container with the quality of the original...

But of course, the filesize will be very big. maybe like 8GB per minute...

.AVI uncomressed is also not so very compatible with various playback units...

mp4 is a great container which you can choose encoding quality..

Depends on what your going to do with the movies/films...

Thanks - I should have been clearer in my original post. I have been using a Sony Z7 and rendering the finished project as the same HDV settings as the original footage (no recompression unless I've added transitions etc), then if required using TMPENC 4.0 xpress to output that as an MP4, WMV for the web or MPEG2 for DVD etc.

I was wondering what settings I should use for the D800 files to get a similar high quality (compressed) output file that could later be brought into TMPGENC?

Well, for what I understand, first you choose which container you want, then you choose the desire bitrate which determinates the quality of your film. Which one you should choose for TMPGENC, im not sure...

If you aiming for loseless, the .AVI container is ideal... For a great compressed format with still great quality, .MP4 is a great one. But there are more.
I use .mp4 with 20bp/s for an output format when I render my videos with my dslr (Canon 60D)...

Thanks, I will experiment with some different settings.

Lately I've been using Lagarith in an AVI container as my DI and mastering format. It is a visually lossless codec that Vegas plays pretty nice with - see if you can open it in Tmpgenc.