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Strobing on slow pans 7D

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Adam Beasley
Strobing on slow pans 7D
on Feb 4, 2011 at 4:13:56 pm

Hi All,

Been shooting with my 7d for a month now, really like it, have come from Digi so there is a fair bit to get used to!

My only real issue thus far is that I am getting awful strobing when panning on a tripod. Doesn't matter what speed, or where I am on the lens (though at the end is worse). Looks fine when shoot it (as far as I can tell at least), when it gets dig'd in the strobing is there!

I'm shooting 25p @ 1/50 - Then going to Pro Res for progressive. But the native files have the strobe on them too...

Oddly, the whip-pan issues I keep hearing about are negligible (hand held stuff doesn't seem to suffer from it),I just can't seem to get a nice slow pan without awful strobing...

I've got fast cards and it's freezing cold here, so it's not those things (I have heard them sited as potential issues..)

Establishers are rubbish without a bit of a move on them, what can I do??


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Malcolm Matusky
Re: Strobing on slow pans 7D
on Feb 4, 2011 at 5:42:04 pm

I noticed this on a few shots, most of my footage is fine. I'll have to do some tests to see how to eliminate the strobing during a pan.

Malcolm
http://www.malcolmproductions.com


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Adam Beasley
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 11:23:17 am

Cool, thanks Malcom


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Rafael Amador
Re: Strobing on slow pans 7D
on Feb 4, 2011 at 8:20:07 pm

[Adam Beasley] "
I'm shooting 25p @ 1/50"

That camera makes p50, doesn't she?
Rafael

http://www.nagavideo.com


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Adam Beasley
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 11:27:59 am

It can shoot 50p, yes but I prefer to shoot 24 or 25 unless I specifically want slow mo stuff...


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Olin Padilla
Re: Strobing on slow pans 7D
on Feb 4, 2011 at 9:05:09 pm

What most people refer to as strobing is caused by an inconsistency between the camera's frame rate and the flicker pattern of the lights used.

If that's what you are talking about, then questions to ask are: What if any lights are you using? Are you in the right part of the world to be shooting 25p? Or is this a different problem altogether?


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Adam Beasley
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 11:29:24 am

I'm based in the UK, so yes, 25p is the norm here. All of the shooting I have been doing is outside so lights have not been a factor.


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Phil Balsdon
Re: Strobing on slow pans 7D
on Feb 4, 2011 at 10:28:39 pm

Where are you viewing the ProRes files, in FCP on broadcast monitor, or in Quicktime?

Cinematographer, Steadicam Operator, Final Cut Pro Post Production.
http://www.steadi-onfilms.com.au/


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Adam Beasley
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 11:30:08 am

All three!


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Phil Balsdon
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 12:05:28 pm

Can you post a few seconds online?

Cinematographer, Steadicam Operator, Final Cut Pro Post Production.
http://www.steadi-onfilms.com.au/


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Adam Beasley
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 8:14:07 pm

Hi Phil,

I've put 3 clips up

http://www.vimeo.com/adambeasley/videos

They are entitled rolling shutter tests 1, 2 & 3

It's worth mentioning here too that I've been using a vision 10, so the head is smooth as you like, though these clips may make it look like that is not the case, hence my problem!


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Rafael Amador
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 9:10:46 pm

I don't see nothing wrong on your pictures. That's the p25 cadence.
If you want something smoother, you need to shoot and edit i50 or p50.
rafael

http://www.nagavideo.com


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Olin Padilla
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 9:28:18 pm

If I saw those clips without reading this thread, I would probably assume it was just a jittery playback.

It sounds like your work flow is pretty solid, so there's no reason to assume any problems were added by the transcode. What you need to figure out is if the (slightly) less than smooth motion is what was actually recorded, or if it's a playback issue. I don't know of anyway to tell for sure without testing it meticulously in different players/formats.

If the jittery motion was recorded in camera and it really bothers you, then I would look into Mocha for After Effects. There are some relatively simple ways to smooth out simple camera motions like this. It's not perfect, and it doesn't work on every shot, but it's worth a try.

Either way, those shots don't look too bad. Nice shooting.


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Adam Beasley
Re: Strobing on slow pans 7D
on Feb 8, 2011 at 2:09:31 pm

Thanks dude, yeah, they don't look quite so bad when online, maybe I'm reading too much into it, but progressive does suffer a bit in this region anyway (I had similar issues with an EX3..) so i guess I'll do some more tests..


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Phil Balsdon
Re: Strobing on slow pans 7D
on Feb 7, 2011 at 9:35:06 pm

Unfortunately the compression for Vimeo introduces a few difficulties in viewing the detail. I also see very little wrong technically.

On shot 1 some shudder maybe caused by the fine detail on the foreground sign. This is probably to do with the pixel shedding necessary to create a 1920 x 1080 image from such a high resolution chip. This is the same problem that results in "moire" patterning and "aliasing" in these cameras.

Shot 2 is panned too fast for a progressive 25p sequence. General rule of thumb is 5 seconds from the time something enters one side of the screen until it exits the other.

Shot 3 compression for online has interfered with being able to evaluate the shot.

Working with HDSLRs really is very similar to shooting 35mm film, you really need to adapt your shooting style to suit the medium. Along with dual system sound, restricted shot duration etc there is learning curve if you're moving over from the interlace video cameras.

Cinematographer, Steadicam Operator, Final Cut Pro Post Production.
http://www.steadi-onfilms.com.au/


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Adam Beasley
Re: Strobing on slow pans 7D
on Feb 8, 2011 at 2:19:07 pm

Thanks Phil,

v-sound advice (the 5 second rule especially, which I was not aware of). To me, the idea that you are not meant to 'whip pan' meant anything slower than a whip should be fine, but I am beginning to see the picture when switching from digi to DSLR..

Clip 3 should be smooth as you like, that stutter is on the clip before I uploaded it, this is the only confusion I now face - as I have said, my tripod is really smooth, I'd be amazed if it is that which is causing that stutter... I will do more tests..

Anyway.. Thanks one and all for the advice, it is much appreciated.

Adam


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