Smooth Slow Motion? at DVinfo.net

Matt Stewart · January 18th, 2010, 05:30 PM

I currently have an HVR-z7u and am using Final Cut Pro to edit. I have been attempting to produce a few slow motion shots, however the stock option on the camera is rather low quality.

I increased the shutter speed to 1200, captured it into FCP and then slowed it down using the basic speed change tool. I believed that the increased shutter speed would give me smooth slo mo when slowed down, but was mistaken. Any insight would be appreciated.

Matt Stewart

Greg Omelchuck · January 18th, 2010, 06:33 PM

I have created great slo mo using the z7 for 24p and 30p. However I use vegas instead FCP. Set the frame rate to 60i 1080. Put the shutter up to 120 or higher, you dont have to go much higher than that. Bring the 60i footage into your NLE of choice. Export that footage out as uncompressed or codec of choice at 60p, I think FCP can do this. Bring that exported footage in FCP in a 24p timeline or 30p timeline and tell FCP that the footage is 24p or 30p and it should playback as slow mo in the timeline. Let me know if that works for you.

Adam Gold · January 18th, 2010, 06:40 PM

When adjusting the shutter speed for slomo, the conventional wisdom is to change the shutter duration in direct proportion to how much you want to slow it down. So, taking 1/60 as "normal" in NTSC-land, if you wanted to slow the footage down by 50% you'd shoot at 1/120, while a 75% slowdown to 25% of normal would mean a recommended shutter of 1/250th or so. Shortening the shutter speed more than that would give you very jittery motion under any circumstances, I think.

And as you noted, the in-cam slomo isn't great.

At least that's the conventional wisdom.

Zach Love · January 20th, 2010, 03:29 AM

How much slow-mo do you need?

I think the 3sec bursts are pretty good quality, not HD, but still look pretty sweet to my eye. The quality does go down a lot when going to 6sec & 12sec bursts.

If you're doing high end slow-motion work, you're going to be spending at least $2k per day on the low end. So to get 120fps out of a $5k camera, we shouldn't be expecting National Geographic quality.

It comes down to if you want the really smooth motion, the lower compression & more stutter.

If you're going to be slowing down in post, I'm not sure how much adjusting the shutter is going to help. I haven't tested it out, but dropping down to 1/120 or 1/250 probably isn't going to make it work all of a sudden.

If I was doing it, I would shoot 1080i60 & have the shutter at 1/60, if the slow-mo bursts didn't work for what I was shooting. But that is me.

January 18th, 2010, 05:30 PM	#1
Matt Stewart New Boot Join Date: Dec 2009 Location: Longview, WA Posts: 6	Smooth Slow Motion? I currently have an HVR-z7u and am using Final Cut Pro to edit. I have been attempting to produce a few slow motion shots, however the stock option on the camera is rather low quality. I increased the shutter speed to 1200, captured it into FCP and then slowed it down using the basic speed change tool. I believed that the increased shutter speed would give me smooth slo mo when slowed down, but was mistaken. Any insight would be appreciated. Matt Stewart

January 18th, 2010, 06:33 PM	#2
Greg Omelchuck New Boot Join Date: Jul 2008 Location: Austin Texas Posts: 22	slo mo I have created great slo mo using the z7 for 24p and 30p. However I use vegas instead FCP. Set the frame rate to 60i 1080. Put the shutter up to 120 or higher, you dont have to go much higher than that. Bring the 60i footage into your NLE of choice. Export that footage out as uncompressed or codec of choice at 60p, I think FCP can do this. Bring that exported footage in FCP in a 24p timeline or 30p timeline and tell FCP that the footage is 24p or 30p and it should playback as slow mo in the timeline. Let me know if that works for you.

January 18th, 2010, 06:40 PM	#3
Adam Gold Inner Circle Join Date: Jan 2007 Location: Woodinville, WA USA Posts: 3,467	When adjusting the shutter speed for slomo, the conventional wisdom is to change the shutter duration in direct proportion to how much you want to slow it down. So, taking 1/60 as "normal" in NTSC-land, if you wanted to slow the footage down by 50% you'd shoot at 1/120, while a 75% slowdown to 25% of normal would mean a recommended shutter of 1/250th or so. Shortening the shutter speed more than that would give you very jittery motion under any circumstances, I think. And as you noted, the in-cam slomo isn't great. At least that's the conventional wisdom. __________________ "It can only be attributable to human error... This sort of thing has cropped up before, and it has always been due to human error."

January 20th, 2010, 03:29 AM	#4
Zach Love Major Player Join Date: Jul 2006 Location: Chicago, IL Posts: 944	How much slow-mo do you need? I think the 3sec bursts are pretty good quality, not HD, but still look pretty sweet to my eye. The quality does go down a lot when going to 6sec & 12sec bursts. If you're doing high end slow-motion work, you're going to be spending at least $2k per day on the low end. So to get 120fps out of a $5k camera, we shouldn't be expecting National Geographic quality. It comes down to if you want the really smooth motion, the lower compression & more stutter. If you're going to be slowing down in post, I'm not sure how much adjusting the shutter is going to help. I haven't tested it out, but dropping down to 1/120 or 1/250 probably isn't going to make it work all of a sudden. If I was doing it, I would shoot 1080i60 & have the shutter at 1/60, if the slow-mo bursts didn't work for what I was shooting. But that is me. __________________ Nothing says you're a serious video maker like S-VHS