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View Full Version : Ramping/Under/Over crank INCAMERA



redindian
01-03-2006, 04:31 PM
Its been established that HVX doesnt do in-camera ramping. But I have a few questions as to why cant we do in post now that we have 60p

Ramping:
So if we shoot in 60p, can we easily do a seemless speed ramp (like velocity env) in Post?

Variable Frame Rates:
Once you shoot 60p - you've got all the frames you need - and u can choose to go from 1fps all the way to 60fps in post... isn't that right? Previously we werent able to do good slowmo with other cameras, coz when we shoot in 24 or 30 we dont have filler frames to fill the gaps.

0xx0xx0xx0xx0xx0xx0xx0xx0xx

0000000000000000000000000

So why do we need 12,22...36,48 and all the other frame rates? Doesn't 60 do pretty much everything? (except it takes double/ triple the file sizes). Or will it work easy only in 10,20,30,40,50,60 (multiples)


Maybe I need to read that frame rate article instead of just looking at the footage :)

mikkowilson
01-03-2006, 04:33 PM
what is one 48th of 60?

redindian
01-03-2006, 04:37 PM
well i am thinking like this...
i have 60 frames...full capacity...
if i want 1fps i pick the first one out of 60 and throw the rest out... now i have 1fps...
if i want 2fps i pick the first, and 30th... now i have 2fps

and so on....

Barry_Green
01-03-2006, 04:51 PM
Doesn't work that way, redindian. As Mikko points out, you can't make 48p out of 60p, it doesn't divide evenly. You can make a sort of simulation of 30p out of 60p, but how do you do 32p? Or 36? Doesn't work.

Two problems with it -- the motion sampling will be incorrect, and the shutter/motion blur will be wrong.

There's no substitute for sampling the frames at the proper cadence and for the proper exposure. That's what makes film look like film, and that's what makes the HVX variable frame rates look like they came from a film camera.

redindian
01-03-2006, 05:01 PM
geniune motion sampling and correct shutter blur....!

yes, it makes sense now... :) thanks mikko & barry...

redindian
01-03-2006, 05:07 PM
also in the same note...

we know that we can do variable rates only at 720p...

but, what happens when a 1080/60i footage is slowed down to 24... does it work as 1080 slowmo?

in other words - why is that 720/60p can do a great slow-mo, and not 1080/60i ? is it coz its interlaced and not progressive?

mikkowilson
01-03-2006, 05:52 PM
60P actually has 60 full frames.
60i only has 60 fields, that's 30 full frames (with or without interlacing artifacts)

so at 60i, you get 30p, so to use in a 24p project you can get a bit of slow-motion, but not nearly as mcuh as with 60p

- Mikko

Barry_Green
01-03-2006, 06:19 PM
Yes you could use 60i to slow down to 30p or 24p, we've been doing that technique on the DVX for years. But the expense is: lower resolution. 60i is only fields, not full frames, so when you turn each field into a frame, it's lower res than the surrounding footage.

dougspice
01-03-2006, 06:26 PM
redindian, to add to what everyone has already said, yes, what you say would work for specific applications. Shooting in 60p would give you the most versatility to change speed in post. But:

1) it will use more storage space
2) it will require more light to shoot