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parenting focus distance to null.
Okay, I’m still a bit inexperienced when it comes to expressions.
I’m trying to parent a camera’s Focus Distance property to a Null Objects Position property.
I alt + clicked on the camera’s fd property and linked it to the Null Position Property.
I thought that would do it.
Obviously I’m missing something.
A little help?
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5 Replies
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Okay, the focus distance seems to be parented to the null’s position, but only it’s X space.
When I move the null side to side, the fd value will change; but not when I move it in Z space, which is what I really need it to respond to.
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Your expression probably looks something like this:
thisComp.layer(“Null 1”).transform.position[0]Change it to this:
thisComp.layer(“Null 1”).transform.position[2]The reason:
0=x 1=y 2=zMake sure you have your null set as a 3D object
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Ahhhhhhhhh, thanks! Changing the position to “2” makes sense.
Thanks!
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The other problem you will have is that a layer that is near the edge of the frame will be farther from the camera than a layer that is at the center of the frame, even if they have the same Z position.
Here’s an expression from Dan Ebberts to correct for this:
https://www.motionscript.com/design-guide/auto-focus.html
Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA -
as long as the null is at the same point as the point of interest you can simply use the length arguement:
length(position, thisComp.layer(“Null 1”).transform.position)
if the null is not then you need to use a little more complicated expression like the one Master Dan has on his site.
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