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Why you have glitch effect on DSLR movment shots?


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#1 Nitai Lev Oren

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Posted 01 July 2016 - 04:29 AM

Here is a video I saw on youtube, and the footage there I saw had a glitch on the movement shots.

and I had the same problem on my DSLR here is a shot from the video:

 

http://screencast.com/t/ngHsTcH5y

 

and here is the full video:

it's in 16:38 - 16:42 

it's a couple of movment shots and there is this artifacts I also get on movement shots on my DSLR

 

I didn't have a shot that I took but it also happens to me on my shots.


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#2 Shawn Sagady

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Posted 01 July 2016 - 04:31 AM

The CMOS scans the image line by line top to bottom, looks like you are seeing an unfinished frame in the buffer or something.  This is why a lot of modern prosumer cameras have rolling shutter based on the speed the sensor is able to scan the lines, it becomes uneven as it goes down while the camera is moving.


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#3 Nitai Lev Oren

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Posted 01 July 2016 - 05:06 AM

there are other types of scans other then the CMOS?


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#4 Brian Drysdale

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Posted 01 July 2016 - 05:31 AM

Some sensors have a global shutter, however, you won't find a global shutter on a DSLR.

 

A number of video camera have small amount of the the rolling shutter artifact, on some it's barely noticiable. DSLRs are stills cameras that take video as the secondary function, so it's not such a poirity in their design.

 

My understanding is that the Blackmagic 4k is the only global shutter large sensor camera in the DSLR price range.


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#5 Nitai Lev Oren

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Posted 01 July 2016 - 06:40 AM

OK I see that in the FS5 there isn't any rolling shutter and C100 have CMOS sensor but they reduced the rolling shutter.

but global shutter cameras you mean CCD cameras?


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#6 Brian Drysdale

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Posted 01 July 2016 - 07:36 AM

The Blackmagic 4k has a CMOS sensor with a global shutter, so not just CCD, although they're not usual.


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#7 Nitai Lev Oren

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Posted 01 July 2016 - 07:40 AM

and if I understand you correct global shutter dismiss rolling shutters completely?


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#8 Brian Drysdale

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Posted 01 July 2016 - 09:18 AM

The different types are explained here:

http://www.red.com/l...rolling-shutter


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#9 Nitai Lev Oren

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Posted 02 July 2016 - 08:07 AM

thanks!

but you know if panasonic cameras like the GH4 have a CMOS sensor or global shutter?


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#10 Tyler Purcell

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Posted 02 July 2016 - 11:51 PM

The GH4 has a CMOS imager without global shutter.

All global shutter does is allow the imager to pulse all it's data at once to the processor, instead of scanning.

The problem here has nothing to do with global shutter.

You need to post a VIDEO of the problem that we can download and analyze, a still isn't good enough.
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#11 Nitai Lev Oren

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Posted 03 July 2016 - 02:32 AM

ok and another question I saw that the C100 has an option to put the shutter on angle mode, so when do I need it?

because I always use the regular increments


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#12 Brian Drysdale

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Posted 03 July 2016 - 04:58 AM

Angle is just another way of setting the same thing. It comes from film cameras with a rotating circular shutter and these were set by the angle the shutter was open. With a film camera at 24 fps 180 degree shutter the exposure is !/48, since the shutter is half open to expose the film during each rotation.


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#13 Nitai Lev Oren

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Posted 03 July 2016 - 05:16 AM

yes but I know but sometimes you have situation you put on less/more then 180 degrees?


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#14 Brian Drysdale

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Posted 03 July 2016 - 06:05 AM

On digital cameras you can because you''re not moving film, however, there is more smear on movement. It's sometimes used to get more exposure on fairly static subjects or a slighly "ghostly" effect with increased motion blur. For general use 180 degrees is taken as the best balance.


Edited by Brian Drysdale, 03 July 2016 - 06:05 AM.

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#15 Nitai Lev Oren

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Posted 03 July 2016 - 06:09 AM

ok but in which industry people use this increment I know everybody works with the regular shutter increments


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#16 Brian Drysdale

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Posted 03 July 2016 - 06:14 AM

I suspect it's mostly film people who are used to using degrees for setting their shutters.


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#17 Nitai Lev Oren

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Posted 03 July 2016 - 06:45 AM

ok, thanks


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#18 Satsuki Murashige

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Posted 03 July 2016 - 01:21 PM

It's important to keep in mind that a 180 degree shutter with a frame rate of 23.976fps results in a shutter speed of 1/47.952, not 1/48. So there is a chance that you could run into 60Hz flicker issues if you choose to use shutter angle mode and not shutter speed mode.

This would not be an issue if you shot true 24.000fps but almost nobody does that with digital cameras. So it's probably safer to just stick with shutter speed for most shooting situations.
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