50p recording for 25p project at DVinfo.net

Nik Skjoth · April 27th, 2009, 01:47 PM

I shot a project in 50p 1/100 shutter, put it in a 25p project timeline. Image is jerky and looks almost as if it was double speed.

Shot another test image in 25p 1/100 shutter, put it in a 25p project timeline. Image looks fine.

Why is there a difference?

How would one go about shooting 50p (for occasional slomo effects) but also make it usefull as regular 25p normal speed footage? I know that 1/50 shutter is way better and smoother, but thats a tradeoff I can live with.. However when recording 50p, the fast shutter is not the only thing making the image unsmooth, and I don't understand why.

Alister Chapman · April 27th, 2009, 02:09 PM

The edit software is probably dropping every other frame to get down from 50fps to 25fps. It has to do something to the original to change the frame rate otherwise it would always be slowmo. Not using any shutter would have looked a bit smoother as you would have ended up with the equivalent to a 180 degree shutter, i.e. the frame only exposed for 50% of the time.

Nik Skjoth · April 27th, 2009, 02:27 PM

naturally the NLE is dropping every other frame. Thats kinda the idea. You could harshly say that 25p recording, is dropping every other frame compared to 50p recording.

Nevertheless... Whether the camera is dropping frames or the NLE does it, should render the same result, but dosn't... question.. why.?

April 27th, 2009, 01:47 PM	#1
Nik Skjoth Regular Crew Join Date: Jul 2007 Location: Cph Denmark Posts: 136	50p recording for 25p project I shot a project in 50p 1/100 shutter, put it in a 25p project timeline. Image is jerky and looks almost as if it was double speed. Shot another test image in 25p 1/100 shutter, put it in a 25p project timeline. Image looks fine. Why is there a difference? How would one go about shooting 50p (for occasional slomo effects) but also make it usefull as regular 25p normal speed footage? I know that 1/50 shutter is way better and smoother, but thats a tradeoff I can live with.. However when recording 50p, the fast shutter is not the only thing making the image unsmooth, and I don't understand why.

April 27th, 2009, 02:09 PM	#2
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	The edit software is probably dropping every other frame to get down from 50fps to 25fps. It has to do something to the original to change the frame rate otherwise it would always be slowmo. Not using any shutter would have looked a bit smoother as you would have ended up with the equivalent to a 180 degree shutter, i.e. the frame only exposed for 50% of the time. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

April 27th, 2009, 02:27 PM	#3
Nik Skjoth Regular Crew Join Date: Jul 2007 Location: Cph Denmark Posts: 136	naturally the NLE is dropping every other frame. Thats kinda the idea. You could harshly say that 25p recording, is dropping every other frame compared to 50p recording. Nevertheless... Whether the camera is dropping frames or the NLE does it, should render the same result, but dosn't... question.. why.?