motion modifier for this?

[illusory]

I'm trying to set something up where I can keep a light behind an object, while the camera moves around the object. In other words, i need to always keep the light on the opposite side of the object from where the camera is, but located hwere the camera would be looking if the object were not in the way. It would also be good to keep the light the same distance from that object, while the camera moves closer and further away.

It's looking like i could maybe use a motion modifier for this, but I haven't really used these before, and from the manual it's not too clear what will work. Channel follower might not be the whole answer.

Can anyone give me some advice how to do this?

thanks,
NJ

[byte_fx]

Simple.

Parent the light to the camera, set x and y values to zero and drag it out on the z until it's behind the object.

If the camera is physically moving closer or further away from the object then parent a null to the camera and the light to null and then scale the null to keep the light the same distance behind if needed.

Or - parent a null to the object and make it point at the camera then parent the light to that null and move it so it's behind the object.

Don't you just love it when an app has several different ways of doing someyhing?

byte_fx

[illusory]

Thanks, byte fx!
Results:
#1 doesn't work
#2 I don't understand the "scale the null to keep the light the same distance behind if needed."
#3 WORKS, except the light doesn't stay the same distance from object, really, but it's close enough!

thanks again!
NJ

[Dodgy]

Why not add the null at the centre of the object, parent both the camera AND the light to it, and point them both at the null. Then only move the camera on the z axis, using the null to rotate them both around it.

[THREEL]

Why not add the null at the centre of the object, parent both the camera AND the light to it, and point them both at the null. Then only move the camera on the z axis, using the null to rotate them both around it.

Dodgy's got it right! But, you probably want to parent the object to the null that represents its center as well. That way if you move the null some where everything parented to it will move as well. The axis you move your camera on will depend on the axis you set everything up on. The default always sets the camera up looking along the z-axis. The other thing you might want to add is targeting. You could target the camera and light on the null or object or you could target the camera and light to "look" at each other.

tHREEL, but you can call me AL.

[illusory]

Thanks guys.
Sounds like the way to go. But in this case, i was trying to avoid targeting the camera because I may want to do some camera matching with Vue down the line. Can do it, but it makes for extra complications. Probably I will ditch the Vue idea anyway though, so....

This gives me some good ideas for a way to work some complicated texture nulls, too!
There's no end to the interesting stuff you can accomplish with nulls, eh? That's probably why i haven't yet resorted to the motion modifiers!

many thanks,
NJ