Scale full frame with crop VS Center crop with no resizing

Hi all, Can someone please explain the difference between the "Scale full frame with crop" VS "Center crop with no resizing " setting.

Heres what I am actually unclear about: If I edit in a HD timeline using UHD footage does it make any difference if I use "Scale full frame with crop" vs" Center crop with no resizing" if I want to want to crop the image eg from a wide shot (original scale) to a closer shot (cropped in) or will this downgrade the footage when I render it out in HD later ? Thank you !

I have upscaled my 1080 HD to UHD and applied a custom aspect ratio of 3840 x 1670. The first pic shows it Full Frame with Crop. The picture fills the frame. The second is Centre Crop no Resizing. So the 1080 frame is in the centre of a 3840 x 1670 frame is at its original size.
If you just want to enlarge part of your picture you can zoom in using the Inspector. Yes there will be some loss, but using a UHD image in an HD timeline will minimize this.

You probably don't want to use either of those options. Use "scale entire image to fit", and reframe the UHD shots as needed with the zoom, tilt and pan controls.

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So if I use the "Full Frame with Crop " setting in a HD timeline with UHD footage and blow up the footage by lets say 50% the quality will be degraded ? Doesnt make sense to me since the UHD footage should have enough resolution not too lose quality in an HD resolution project if I dont blow it up more than 4 times its size. I did it in Premiere all the time. In Premiere though I would use "Set to frame size" instead of "Scale to frame size" with UHD footage in an HD timeline and then scale it the way I wanted. So I wonder if the "Full Frame with Crop" setting in Resolve is like the "Scale to frame size" in Premiere (basically converting the UHD footage to HD) or more like "Set to frame size" in Premiere where I dont lose any pixels of the UHD footage and can crop in etc without losing quality within the HD project ?

You probably don't want to use either of those options. Use "scale entire image to fit", and reframe the UHD shots as needed with the zoom, tilt and pan controls.

viewtopic.php?f=21&t=99202

Aha !! I think this is the answer I was looking for ! Thank you !!!!!