Reflection abruptly fallsoff

[asifa]

I'm experience a strange issue where if i move my Back plate image (plane) A very small amount (x direction) the reflection completely disappears. Perhaps i'm misunderstanding how the eye works but it seems strange that it falls off so abruptly. See attached.
I've played with the Dim distance on both objects and that doesn't seem to correct the issue. Currently using Max 2015 and Vray 3.5

[Art48]

Doesn't look exactly like that issue but try to adjust the cutoff value in the Options tab of the VRayMtl. Set it to 0.001 in case it is not set to that value already. It should be the default.

[Raven]

To me, it looks like you have a light that is now in front of the backplate plane, so it is reflecting instead of the plate.

[asifa]

Raven! im so stupid thanks! that was it!! rookie move