Question to slow motion at DVinfo.net

Peter Berger · October 29th, 2011, 09:02 AM

I wanna try to make some slow motion clips with Twixtor plugin and I am wondering, what is the best shutter speed for this? The second question - I have Canon 5D MII which doesnt have 50/60p, so what frame rate should I choose? The result will be probably in 24p or 25p.

John Wiley · October 30th, 2011, 01:10 AM

Use a very fast shutterspeed - at least 1/250th of a second to eliminate motion blur. The shraper your images to start off with, the more data Twixtor has to work with and the more accurate it will be.

If you know exactly what shots you want to slow down, shoot them at 30p. Then conform to 24p or 25p in post before appyling Twixtor. If you don't know which shots you want to slow down, or if you might want to use the shots at real time, then just shoot at whatever frame rate the project will be edited in.

Peter Berger · October 30th, 2011, 09:38 AM

I have to do some tests. I think with very fast shutter speed it could lookl clean but jittery... or not? Maybe I need to find the optimal shutter speed where the picture is not jittery...and it's not too blurred.

John Wiley · November 1st, 2011, 05:43 AM

It will be jittery until you apply Twixtor. When you slow it down Twixtor will create new frames inbetween and smooth things out.

To be able to work properly, Twixtor needs a sharp image with no motion blur, otherwise it is unable to track and predict motion accurately enough to create the inbetween frames properly.

'Natural' motion blur is directly related to frame rate - inlcuding the playback frame rate. Playing back 24p footage with a shutterspeed of 1/50th looks natural at real-time, but slow it down or pause on a single frame and you'll notice blur all over the place - and the same applies when slowing footage down with Twixtor. Shooting footage with a 'regular' shhutter speed will also appear unnatural because Twixtor simulates footage being shot at a fast frame rate - if the footage is actually shot at a faster frame rate, having a shutter speed of 1/60th or 1/50th would defy physics.

October 29th, 2011, 09:02 AM	#1
Peter Berger Regular Crew Join Date: Apr 2009 Location: Czech Republic Posts: 136	Question to slow motion I wanna try to make some slow motion clips with Twixtor plugin and I am wondering, what is the best shutter speed for this? The second question - I have Canon 5D MII which doesnt have 50/60p, so what frame rate should I choose? The result will be probably in 24p or 25p.

October 30th, 2011, 01:10 AM	#2
John Wiley Trustee Join Date: Oct 2008 Location: Byron Bay, Australia Posts: 1,155	Re: Question to slow motion Use a very fast shutterspeed - at least 1/250th of a second to eliminate motion blur. The shraper your images to start off with, the more data Twixtor has to work with and the more accurate it will be. If you know exactly what shots you want to slow down, shoot them at 30p. Then conform to 24p or 25p in post before appyling Twixtor. If you don't know which shots you want to slow down, or if you might want to use the shots at real time, then just shoot at whatever frame rate the project will be edited in.

October 30th, 2011, 09:38 AM	#3
Peter Berger Regular Crew Join Date: Apr 2009 Location: Czech Republic Posts: 136	Re: Question to slow motion I have to do some tests. I think with very fast shutter speed it could lookl clean but jittery... or not? Maybe I need to find the optimal shutter speed where the picture is not jittery...and it's not too blurred.

November 1st, 2011, 05:43 AM	#4
John Wiley Trustee Join Date: Oct 2008 Location: Byron Bay, Australia Posts: 1,155	Re: Question to slow motion It will be jittery until you apply Twixtor. When you slow it down Twixtor will create new frames inbetween and smooth things out. To be able to work properly, Twixtor needs a sharp image with no motion blur, otherwise it is unable to track and predict motion accurately enough to create the inbetween frames properly. 'Natural' motion blur is directly related to frame rate - inlcuding the playback frame rate. Playing back 24p footage with a shutterspeed of 1/50th looks natural at real-time, but slow it down or pause on a single frame and you'll notice blur all over the place - and the same applies when slowing footage down with Twixtor. Shooting footage with a 'regular' shhutter speed will also appear unnatural because Twixtor simulates footage being shot at a fast frame rate - if the footage is actually shot at a faster frame rate, having a shutter speed of 1/60th or 1/50th would defy physics.