Ghosting, why am I seeing it?

David Newman · December 27th, 2008, 07:26 PM

The Adobe AVC Decoder is fine (CS4 is not.) The pulldown is removed correctly. When comparing the 60i to resulting 24p extraction, there is zero motion blur added. The is some frame presistance inherent in the camera, no more than I've seen in all the sub-$1000 progressive cameras.

Mario Jesmanowicz · December 27th, 2008, 08:58 PM

so basically 24p on Canon's is useless (which goes for all the HV-20,30 and HF100, 10 11 and HG-20 and 21 :)

thanks

David Newman · December 27th, 2008, 09:53 PM

Not at all, I would shoot all of them over any interlaced source. It just not film, or digital cinema.

Chad Haufschild · December 27th, 2008, 10:41 PM

Hey, Mario. I think what you're seeing has less to do with Cineform and the original codec and more to do with what was shot.

If you have a guy walking from one side of the frame to the other, you might be seeing what some people call "motion jitter" and others call "ghosting" which is caused by how the subject moves across the frame. I'm sure you've heard or read this before, but shooting 24p video is more like shooting film than it is like shooting 60i video. There are rules to follow to avoid that "ghosting."

There's a bunch of threads on this forum that describe those rules so I won't bore anyone with the details, but the number one thing to avoid when shooting 24p is having the subject move across a static frame from one side to the other. Movement toward the camera and away from the camera is fine, but not across it. 24 frames just aren't enough to capture the motion correctly unless the subject is traveling at a pretty slow speed.

My suggestion is to go back to Best Buy and shoot someone walking towards the camera, walking away from the camera, and panning with the person as they walk by and see if you get the same results.

Sorry if you've heard this all before.

By the way, the HV30 (tape-based HDV) shoots pretty good 24p. I've use mine as a b-cam and mix it with my JVC HD250 after down-converting the video to 720 during capture with HDlink. Good job Canon and Cineform.

Mario Jesmanowicz · December 28th, 2008, 10:44 AM

Chad

now this makes sense what you are saying. But comon, I was watching few movies in the last days and I watched and paid attention to their movement and they did walk across the frames smoothly

But I can see how 60Hz indoor light and not paying attention to shutter could have caused the issues I had. Isn't there something that says I should use either 1/24 or 1/48 shutter speed?

but I still think that 60Hz light was the main cause of my problem

Chad Haufschild · December 28th, 2008, 01:17 PM

Shutter speed can definitely cause issues. I shoot 24p exclusively at 1/48. 1/24 look really bad. Higher shutter speeds can give you less of that jitter but can cause the movement to seem less natural like that now classic "Saving Private Ryan" look. They used fast shutters in "Gladiator," too, to give that super-fast action look.

However, stuff shot on film still has a different look than shooting 24p video. We have to deal with those electonic related issues that film doesn't have. The motion issues we're dealing with seem magnified with 24p video. It's just one of the disadvantages of the format.

I remember watching a Hollywood film-originated romantic comedy with my wife (she likes that stuff so what can I do) and seeing that very motion jitter that we're talking about. It was far less noticable than it would have been if it were shot with 24p video, but it was still there. It actually made we feel pretty good. If they big boys still have to deal with it than I'm not such a bad shooter after all!

I've never really considered the lighting being a contributor, but it makes some sense to me that it might. Maybe someone else could jump in on that front.

Mario Jesmanowicz · December 28th, 2008, 04:20 PM

well 60Hz that is on and off every 1/60 of a second and you shoot 24, that can effect it

BUT about movies. I see it all the time and see more problems that are like "well they should have taken care of it"

like wrong clothes that will make video/film cause issues
panning I see all the time, especially on buildings, cities, they sometime do it just a bit too long at it is annoying (makes me feel better too that they miss it...)
also look at the headlights on the cars, they show reflections which is because of the lens

but just walking people weather close of far away I never saw ghosting there even across the frame wchich is common in the movies when they walk and talk.

December 27th, 2008, 07:26 PM	#16
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	The Adobe AVC Decoder is fine (CS4 is not.) The pulldown is removed correctly. When comparing the 60i to resulting 24p extraction, there is zero motion blur added. The is some frame presistance inherent in the camera, no more than I've seen in all the sub-$1000 progressive cameras. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

December 27th, 2008, 09:53 PM	#18
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	Not at all, I would shoot all of them over any interlaced source. It just not film, or digital cinema. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

December 27th, 2008, 08:58 PM	#17
Mario Jesmanowicz Regular Crew Join Date: Apr 2007 Location: Milwaukee WI USA Posts: 55	so basically 24p on Canon's is useless (which goes for all the HV-20,30 and HF100, 10 11 and HG-20 and 21 :) thanks

December 27th, 2008, 10:41 PM	#19
Chad Haufschild Regular Crew Join Date: Nov 2006 Location: Lincoln, NE Posts: 162	Hey, Mario. I think what you're seeing has less to do with Cineform and the original codec and more to do with what was shot. If you have a guy walking from one side of the frame to the other, you might be seeing what some people call "motion jitter" and others call "ghosting" which is caused by how the subject moves across the frame. I'm sure you've heard or read this before, but shooting 24p video is more like shooting film than it is like shooting 60i video. There are rules to follow to avoid that "ghosting." There's a bunch of threads on this forum that describe those rules so I won't bore anyone with the details, but the number one thing to avoid when shooting 24p is having the subject move across a static frame from one side to the other. Movement toward the camera and away from the camera is fine, but not across it. 24 frames just aren't enough to capture the motion correctly unless the subject is traveling at a pretty slow speed. My suggestion is to go back to Best Buy and shoot someone walking towards the camera, walking away from the camera, and panning with the person as they walk by and see if you get the same results. Sorry if you've heard this all before. By the way, the HV30 (tape-based HDV) shoots pretty good 24p. I've use mine as a b-cam and mix it with my JVC HD250 after down-converting the video to 720 during capture with HDlink. Good job Canon and Cineform.

December 28th, 2008, 10:44 AM	#20
Mario Jesmanowicz Regular Crew Join Date: Apr 2007 Location: Milwaukee WI USA Posts: 55	Chad now this makes sense what you are saying. But comon, I was watching few movies in the last days and I watched and paid attention to their movement and they did walk across the frames smoothly But I can see how 60Hz indoor light and not paying attention to shutter could have caused the issues I had. Isn't there something that says I should use either 1/24 or 1/48 shutter speed? but I still think that 60Hz light was the main cause of my problem

December 28th, 2008, 01:17 PM	#21
Chad Haufschild Regular Crew Join Date: Nov 2006 Location: Lincoln, NE Posts: 162	Shutter speed can definitely cause issues. I shoot 24p exclusively at 1/48. 1/24 look really bad. Higher shutter speeds can give you less of that jitter but can cause the movement to seem less natural like that now classic "Saving Private Ryan" look. They used fast shutters in "Gladiator," too, to give that super-fast action look. However, stuff shot on film still has a different look than shooting 24p video. We have to deal with those electonic related issues that film doesn't have. The motion issues we're dealing with seem magnified with 24p video. It's just one of the disadvantages of the format. I remember watching a Hollywood film-originated romantic comedy with my wife (she likes that stuff so what can I do) and seeing that very motion jitter that we're talking about. It was far less noticable than it would have been if it were shot with 24p video, but it was still there. It actually made we feel pretty good. If they big boys still have to deal with it than I'm not such a bad shooter after all! I've never really considered the lighting being a contributor, but it makes some sense to me that it might. Maybe someone else could jump in on that front.

December 28th, 2008, 04:20 PM	#22
Mario Jesmanowicz Regular Crew Join Date: Apr 2007 Location: Milwaukee WI USA Posts: 55	well 60Hz that is on and off every 1/60 of a second and you shoot 24, that can effect it BUT about movies. I see it all the time and see more problems that are like "well they should have taken care of it" like wrong clothes that will make video/film cause issues panning I see all the time, especially on buildings, cities, they sometime do it just a bit too long at it is annoying (makes me feel better too that they miss it...) also look at the headlights on the cars, they show reflections which is because of the lens but just walking people weather close of far away I never saw ghosting there even across the frame wchich is common in the movies when they walk and talk.