Shutter angle/frame rate to avoid jitter

E

ebsseattle

Active member
I notice that sometimes my camera will give me a bit of a jittery image. My intuition tells me it may have something to do with the correlation between the shutter angle and frame rate. Is there some guide or rule that provides recommendations on ways of avoiding this jitter, or sputtering look?
 
Do you mean it should be double the framerate as a minimum, or it should always be divisible by 24? (24, 48, 72, 96, etc?)
 
ebsseattle said:
I notice that sometimes my camera will give me a bit of a jittery image. My intuition tells me it may have something to do with the correlation between the shutter angle and frame rate. Is there some guide or rule that provides recommendations on ways of avoiding this jitter, or sputtering look?
Click to expand...

The generally accepted 'shutter angle' is 180 (or slight deviations of that to account for the frequency of power to the lights.). For most DSLR shooters, that means 1/50 is the nearest standard shutter speed.

That said, there are some people in the Lumix GH-x section that recommend 1/40.

That that said...
.
just saying 'my image is jittery', doesn't lead to a specific condition for which there is a well known solution.

Assuming the motion of the object is smooth, jittery image could be one of the following(if not more...):

Shutter speed not correct for the speed of the object in motion.
Object's horizontal or vertical motion is such that well known motion artifacts can be observed.
Camera sensor and related 'read out' or compression technique may impact motion artifacts
Computer and computer program used to display clip can produce 'jitter'.

If the camera is setup for 24 fps, and the shutterspeed is 1/40 or 1/50, and the object moves across the screen at a rate of 'full screen width, in 5 seconds or more', and the motion has 'jitter', then it may be due to
computer and software used to display.

Other assumptions include camera mounted on tripod, and the camera is in working order.
 
You should have in mind that 24fps at 180 degree shutter (1/48s) is jittery. That is, cinema IS jittery.
If you want smooth motion you should increase the framerate, or decrease the shutter speed (increase the shutter angle). Or both.
More on shutter speeds, frame rate and cinema.
 
Here's a sample of a short clip I shot where I noticed the jittery image issue I'm talking about. Video was shot at 24fps but I don't know the shutter angle.
[video=metacafe;9453583/lab/]http://www.metacafe.com/watch/9453583/lab/[/video]
 
ebsseattle said:
Here's a sample of a short clip I shot where I noticed the jittery image issue I'm talking about. Video was shot at 24fps but I don't know the shutter angle.
[video=metacafe;9453583/lab/]http://www.metacafe.com/watch/9453583/lab/[/video]
Click to expand...

You're panning far too quickly. You can't move the camera like that and get smooth motion at 24 fps. You need to have much slower camera movements.
 
ebsseattle said:
Here's a sample of a short clip I shot where I noticed the jittery image issue I'm talking about. Video was shot at 24fps but I don't know the shutter angle.
[video=metacafe;9453583/lab/]http://www.metacafe.com/watch/9453583/lab/[/video]
Click to expand...

There is something odd happening there causing frames to be duplicated. Did you possibly shoot at a different frame rate to the final render?
 
Bad export, its funny how posting video reveals true problem.Its not jitter caused by camera, its filmed with different fps than export fps setting.
 
There's no reason to think that's a bad export until the OP confirms it doesn't look that in his raw footage. It looks like typical stutter produced by panning as quickly as he does.
 
bwwd said:
Bad export, its funny how posting video reveals true problem.Its not jitter caused by camera, its filmed with different fps than export fps setting.
Click to expand...

No, it's not. The export is identical in framerate and compression as the raw material. But nice try!
 
Last edited:
I just imported the footage into Premiere. Frames 2 and 3 are identical. So are frames 7/8, 12/13, 17/18, 22/23, 27/28, 32/33, 37/38, 41/42 etc.
 
ebsseattle said he shot at 24fps, but that clip is at 30fps. Either he changed the frame rate, or perhaps Metacafe changed it.
 
You must log in or register to reply here.
Back
Top