Slow Shutter Light Trails Cutoff?

[3dgeek]

Hello, I am trying to reproduce the effect of leaving the shutter open while moving light around to create trails.

I know that it can be done through scripts that generate a trail of geometry (I've done this before) but I am wanting to do it in a real world way.

My procedure has been:
Create a spline, make it a renderable tube.
Animate it moving in front of the camera over 30frames.
Assign a vray light material
Put a vray cam in the scene
turn on motion blur
set shutter speed to 1
Set motion blur samples on the object to 100
While I am getting trails... it seems they are cut off at a certain point... in other words... they don't "stay on" like I am trying to achieve. You can see the cut off on the left side in the image below... the light stick moves from the far left side of the screen twisting the whole way..

Any ideas how to accomplish this?
Is there some "cut off" setting I am unaware of?

Thank you.
Chuck

ps.
My other settings...
DMC
GI BF

[trixian]

Shutter speed.
You set it to one frame duration.
Set it to whatever fits for your animation length
?????
Profit

[Da_elf]

30 frames is 1 second. you set the shutter speed to 1 second. therefore the cutoff is because its showing where it started and where it ends all in that 1 second the shutter was open. try to have the shutter speed not quite 1 second or have the animation longer

[trixian]

Yes, sorry meant one second.
Had the image of the camera roll-out in the render dialogue's motion blur settings in my mind, where the parameter is 1 for one frame etc.

Like Da elf said, anything lower than 1 would let you extend the duration of the motion blur.

[3dgeek]

First, thank you for the suggestions.

So I've tried in the vray cam settings to go lower than 1 to .2, .o1 ect... and it still does not capture the entire animation. Maybe I am not understanding... I've attached the scene if anyone has the time to look at it.

spline test.zip