Dark Shadows using vray material with refraction

[ratus69]

Hello,
I'm having dark regions when rendering with vray (RT CPU or GPU) for modo in this example
I've tried ro increase trace depth but it's still very dark compared to modo render
Any suggestions ?
Thanks

[ratus69]

Ok I found out that to reduce black shadows with refraction, I need to uncheck "Lock fresnel IOR" and set a value of 0.5 for fresnel IOR and now I'm close to the modo render