I want to export ONLY Depth channel to a file.
But when rendering mantra node,`C`channel is always exported with Depth channel.
Now I want ONLY the depth information.
So I want houdini not to calculate channels such as diffuse,reflect so on to speed up rendering.
Is there any way to do it?

Maybe one way is :
1. Create new Take for Depth Rendering
2. Turn On "Matte Shading" parameter for all of the objects in this Take
3. Render your project for this Take

Now all of the objects should skip in C rendering and you should take BLACK image only for C channel . :?

Thank you for your advice.
Good idea 8)
This seems to be the only way.
I tried to manage to remove C channel regardless of the need.
As rendering a bunch of frames,vain black images are generated :cry: