How does MC deal with UHD media in an HD project.

For example, if I scale up the UHD material in HD project, does it maintain the quality of the UHD footage?  i.e. does it scale up the UHD, or is it converting it to HD in the background, and just scaling up that HD version?

Should I switch to UHD scale up and mixdown before returning to the HD environment?

I have 2 versions of the footage in HD and UHD, and I have done a test and I can see no difference between the UHD scale up and the HD scale up which makes me concerned that MC is only using an HD version fo the material when I am in HD project.

Thanks

After more testing, as far as I can work out, if you are in HD project, then your UHD material is treated as HD regardless of whether you use pan and scan or DVE to scale up.   Seems very odd to me, that you cannot work with UHD in an HD project....?  WIthout constantly switching to UHD to render any scaling.

And even more bizarre, you have to mixdown the scale ups in UHD if you want to see them in HD???

Not sure if I'm reading your post correctly, but I'll offer this: I routinely bring UHD footage into an HD project, and it scales it accordingly and it looks fine. I then routinely go to source/frameflex on certain shots and scale as needed to "punch in" (as in an interview to get a different shot), and it also looks fine if it's less than 200%. HTH.

As ronn explained, Frameflex will automatically resize your UHD footage to fit your project settings. You can change this behaviour and zoom further in/reframe/rotate your image by adjusting these settings within Frameflex. 

In theory you should be able to zoom in by 400% without any loss in quality, since UHD has four times the pixel count of HD.

Note that when you use Frameflex on a master clip, it will effect every instance of the clip on your timeline. Also note that if you make Frameflex changes to your master clip after you've added these clips to your timeline, you won't see the changes until you refresh your sequence.

If you want to resize a clip differently once it's on the timeline, you can open up your Effects Editor and you'll see the Framflex as an effect that you can manipulate/keyframe etc., just like a regular effect. This will only effect that instance of the clip on the timeline.

What you cannot do is apply the regular Avid resize effects as this will not act on the original UHD material.

It's 200% enlargement - 1080 (HD) x 2 = 2160 (UHD) and 1920 x 2 = 3840.

It's 4 times the pixels (HD = 2,073,600 pixels. UHD = 8,294,400 pixels) but 2x the dimension.