HD Monitoring for UHD timelines

Please make it possible to monitor UHD/4K timelines on HD monitors.

UHD timeline plays quite happily on my HD monitors. If the timeline resolution and/or Video Monitoring is set to UHD or FHD the UHD timeline plays fine here.
Here is a UHD timeline playing on my HD monitor. This is Video Clean Feed, but it's just as happy using the Cinema Viewer.

Works fine for me. The key is to have the exact same aspect ratio in HD that you do in 4K. So (for example), don't expect to monitor 4096x2160 on a 1920x1080 frame, because the aspect ratios are not identical. You can monitor 3840x2160 on a 1920x1080 set and still see the entire image area.

Thank for your responses. I don't get it to work!
- I have a 16:9 - UHD timeline
- BM Ultrastudio monitor is set to FHD and selected as Video IO device

The monitor will only show a center cropped image. Of course the viewer is showing the UHD image.
What I want is for the viewer to show the UHD image and the monitor receiving an FHD stream.
Which magic settings do I have to tweak to make this work?

UHD timeline plays quite happily on my HD monitors. If the timeline resolution and/or Video Monitoring is set to UHD or FHD the UHD timeline plays fine here.
Here is a UHD timeline playing on my HD monitor. This is Video Clean Feed, but it's just as happy using the Cinema Viewer.

Hi Charles,
Thank you for your tip. I am not using video clean feed, but an external video IO device (blackmagic monitor 3g). Clean feed will always work, that is no problem.