Why different magnification when choosing between Scale vs Set to frame size?

[good_knight]

Have mpg 1920x1080i30 video clips in a 1920x1080p60 sequence (frame rate unimportant). The dimensions are the same is whats important. When choosing Set to Frame Size, the Effect Controls panel's Scale reveals a 220% increase to fill the frame. But, when choosing Scale to Frame Size, the Scale is 100% to fill the same frame size. Why? Which would you expect to offer better quality in this case? Or, is there something or some hidden setting scewing the result? (Premiere Pro 2024; TB3 SSD hardware.)

[Peru Bob]

See here:

https://www.google.com/search?q=helpx+set+tio+frame+size+vs+scale+to+frame+size&rlz=1C1CHBF_enUS776U...

and here:

https://community.adobe.com/t5/premiere-pro-discussions/set-to-frame-size-vs-scale-to-frame-size/td-...

[good_knight]

Already explored, Bob. The question should perhaps be: Why am i getting a 220% scale when i was expecting a 100% for the same dimensions frame? Or, how do i get a 100% scale when selecting Set to Frame Size?

[Richard van den Boogaard]

Question: if the size of the source footage and the destination sequence are identical, why would you use either Set to Frame Size or Scale to Frame Size? What is there to size up?

[good_knight]

So, Richard, why is Set to Frame size reading 220% to fill the frame? Why isn't it reading 100%?

[Richard van den Boogaard]

If it ain't broke, don't try to fix it... again, why would you even use these features if the dimensions of the clips and the sequence are identical?

I have no idea why the Set to Frame Size reads 220%. Perhaps it has something to do with the difference in framerate (unlikely) or the fact that it is interlaced (i) footage you're adding to a progressive timeline.

[Ann Bens]

Post screenshot sequence settings and clip properties.

Effect controls : one for FIT and one for SCALE.