720pn vs 1080i post slow motion

D

DeadEyesSmiling

Well-known member
Hello there,

I've been looking into this for a while and it seems that there is an aversion to shooting 1080/60i and interpreting it as 24p in post to create slow motion.

I'm looking for an explanation on why this is a worse way to go over the native capabilities of 720/24pn @60fps.

Thanks!

-DES
 
Hi DeadEyes,

60i equates to sixty 'half frames' called fields, recorded in a roughly 30fps time base. That's one field every 1/60 of a second. Your subject is going to move between each field. The resulting differences when the fields are interlaced give the video a comb like effect on anything that is in motion.

Shooting 60p equates to sixty full frames, or progressive frames recorded in a roughly 60 fps timebase. That one discrete frame every 1/60 or a second. Playing back 60p recorded footage at a 24fps timebase results in true 2.5 times slow motion.

In order to get a progressive frame from 60i, you need to de-interlace, which effectively creates 30p video. 30p played back at 24fps results in 1.25 times slow motion. You will never get a slow and as smooth a slow motion with 60i as you will with 60p.

Another option is to use an interpretative software such as twixtor to get super slow super smooth slow motion. Still, you would be better off shooting at 120, 360, 1000 or more progressive fps to begin with and avoiding all of the hassle of 'faking it in post'.


Jason
 
You must log in or register to reply here.
Back
Top