Slow motion; 50i or 60i at DVinfo.net

Vedran Rupic · October 2nd, 2007, 12:39 PM

Hello,

I posted a similar question on the z1 board but haven't had any replies.
I'm shooting a video that's gonna contain some slow-mo shots.
The camera I will be using is a Sony HVR-Z1, which is PAL/NTSC switchable.
Now the final delivery will be PAL, and most likely progressive.

Now for the question. Should I set the camera to 60i when shooting the slow-mo sequence in order to achieve a higher temporal resolution?
The technique I'm about to use is the "convert fields to frames", Is this a good idea? Most likely, there will be some twixtoring involved as well.
Any input is very appreciated as I'm beginning to feel desperate.

Kindest Regards,
Vedran

Daniel Ross · October 2nd, 2007, 01:13 PM

It's a tradeoff. Using fields will allow 60 half resolution frames per second. Using 30p will be 30 full resolution frames at fewer intervals.
60 in that sense is better for motion and you probably won't notice a huge difference in quality.
However, if you're using a plugin (probably a good idea), then that may do better with more resolution. Or with more motion. It's hard to know without testing.

I'd say definitely shoot 30p/60i because that's just more than 25/50.

Even if you ran it at one frame per second, you'd have 20% slower footage at full resolution using 30p within 25p.

The only reason not to go with 30/60 is if you want a specific ratio to 25p, such as 50%, best achieved by using 25/50/etc.

Vedran Rupic · October 3rd, 2007, 04:24 AM

Thanks Daniel,

I figured that 60i was the best solution, unfortunatley I cannot shot 30p with the Z1.
Besides, the final should be in SD PAL, and I'm shooting with a hdv camera, so I guess the resolution loss won't be that bad since I'm downsampling.

Is there any problems (NLE wise that is) that I can run into if i try to make this footage into 25p in the end?

thanks

Jack Zhang · October 3rd, 2007, 06:35 AM

Drop frame might be an issue... But using Vegas I slowed down my 60i footage to 25p by discarding one field via the Interpolation option in the De-interlace property in my project properties. Worked surprisingly well. Don't know about doing this without discarding a field.

Vedran Rupic · October 3rd, 2007, 07:49 AM

Allright, so it's possible.
I will be using AE, since all plugins are there.
I'm glad someone has tried it, I don't feel like messing up a shot completly just because I capture the images in a wrong way.
Anyone done this in AE?

Best regards,

Daniel Ross · October 3rd, 2007, 03:39 PM

Twixtor is one plugin, and so is Kronos, but that algorithm is now built into the embedded time remapping function in AE7+. There are others, too. Adding motion blur back in, or removing it, might be something to play with as well.
I'd also suggest shooting as best you can to make it a bit slower than "real life", IF the motion doesn't look wrong (might not be possible).

60i is fine, especially downsizing to SD then.

I don't see drop frame being a problem here. Simply remove any time data from the clip by converting 30 to 25, then you will do what you want. From there, you can slow as much as you want. Remapping 30 to 25 will just make it a bit slower. No harm done. Drop frames as you want-- or don't. Just play the 60i footage as 50i, and you're done.

Vedran Rupic · October 4th, 2007, 04:44 AM

Thank you guys!
I'm relieved as of now.

October 2nd, 2007, 12:39 PM	#1
Vedran Rupic Regular Crew Join Date: May 2006 Location: Örebro, Sweden Posts: 71	Slow motion; 50i or 60i Hello, I posted a similar question on the z1 board but haven't had any replies. I'm shooting a video that's gonna contain some slow-mo shots. The camera I will be using is a Sony HVR-Z1, which is PAL/NTSC switchable. Now the final delivery will be PAL, and most likely progressive. Now for the question. Should I set the camera to 60i when shooting the slow-mo sequence in order to achieve a higher temporal resolution? The technique I'm about to use is the "convert fields to frames", Is this a good idea? Most likely, there will be some twixtoring involved as well. Any input is very appreciated as I'm beginning to feel desperate. Kindest Regards, Vedran __________________ Documentary work

October 3rd, 2007, 04:24 AM	#3
Vedran Rupic Regular Crew Join Date: May 2006 Location: Örebro, Sweden Posts: 71	Thanks Daniel, I figured that 60i was the best solution, unfortunatley I cannot shot 30p with the Z1. Besides, the final should be in SD PAL, and I'm shooting with a hdv camera, so I guess the resolution loss won't be that bad since I'm downsampling. Is there any problems (NLE wise that is) that I can run into if i try to make this footage into 25p in the end? thanks __________________ Documentary work

October 3rd, 2007, 07:49 AM	#5
Vedran Rupic Regular Crew Join Date: May 2006 Location: Örebro, Sweden Posts: 71	Allright, so it's possible. I will be using AE, since all plugins are there. I'm glad someone has tried it, I don't feel like messing up a shot completly just because I capture the images in a wrong way. Anyone done this in AE? Best regards, __________________ Documentary work

October 4th, 2007, 04:44 AM	#7
Vedran Rupic Regular Crew Join Date: May 2006 Location: Örebro, Sweden Posts: 71	Thank you guys! I'm relieved as of now. __________________ Documentary work

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October 2nd, 2007, 01:13 PM	#2
Daniel Ross Major Player Join Date: Jul 2007 Location: Marin & Davis, CA, USA Posts: 418	It's a tradeoff. Using fields will allow 60 half resolution frames per second. Using 30p will be 30 full resolution frames at fewer intervals. 60 in that sense is better for motion and you probably won't notice a huge difference in quality. However, if you're using a plugin (probably a good idea), then that may do better with more resolution. Or with more motion. It's hard to know without testing. I'd say definitely shoot 30p/60i because that's just more than 25/50. Even if you ran it at one frame per second, you'd have 20% slower footage at full resolution using 30p within 25p. The only reason not to go with 30/60 is if you want a specific ratio to 25p, such as 50%, best achieved by using 25/50/etc.

October 3rd, 2007, 06:35 AM	#4
Jack Zhang Inner Circle Join Date: May 2005 Location: Burnaby, BC, Canada Posts: 3,053	Drop frame might be an issue... But using Vegas I slowed down my 60i footage to 25p by discarding one field via the Interpolation option in the De-interlace property in my project properties. Worked surprisingly well. Don't know about doing this without discarding a field.

October 3rd, 2007, 03:39 PM	#6
Daniel Ross Major Player Join Date: Jul 2007 Location: Marin & Davis, CA, USA Posts: 418	Twixtor is one plugin, and so is Kronos, but that algorithm is now built into the embedded time remapping function in AE7+. There are others, too. Adding motion blur back in, or removing it, might be something to play with as well. I'd also suggest shooting as best you can to make it a bit slower than "real life", IF the motion doesn't look wrong (might not be possible). 60i is fine, especially downsizing to SD then. I don't see drop frame being a problem here. Simply remove any time data from the clip by converting 30 to 25, then you will do what you want. From there, you can slow as much as you want. Remapping 30 to 25 will just make it a bit slower. No harm done. Drop frames as you want-- or don't. Just play the 60i footage as 50i, and you're done.