Compositor beginner here:

I have this compositing node tree:

enter image description here

why does Blender render my second viewlayer, although i don't use it in the compositor?

enter image description here

My stupid assumption was, that i could render faster (i had the VL2 layer before instead of the image input), if i just use a static picture as background. But looks like Blender doesn't think like i do....umpf


if i disable the render buttons in VL2, it does what i want.

But really i hoped Blender does something like in GN, if nodes are not used, it wouldn't execute it :(

enter image description here

  • $\begingroup$ Are you sure you haven't loaded it in the Video Sequencer? $\endgroup$
    – moonboots
    Commented Feb 17 at 20:07
  • $\begingroup$ yes i am sure.... $\endgroup$
    – Chris
    Commented Feb 17 at 20:07
  • $\begingroup$ You should not have to disable anything in VL2 if it is not selected in the Render Layers node $\endgroup$
    – moonboots
    Commented Feb 17 at 20:18
  • $\begingroup$ maybe make your file very simple (replace the robot by a cube) and share your file? $\endgroup$
    – moonboots
    Commented Feb 17 at 20:25
  • 1
    $\begingroup$ In all my explanations in the answer I forgot to mention, one of the reasons view layers get rendered even though not used in the Compositor: this is post-processing. It does not affect what Blender hands over to the render engine to get rendered. It only affects the output if you plug nodes inbetween. You could also disable the Compositor to render a scene. The only thing is, if it is enabled and nothing is plugged into the Composite node (or there is none), then Blender won't render at all and give an error message for not having anything to output. $\endgroup$ Commented Feb 18 at 18:20

1 Answer 1


Blender renders all view layers which have Use For Rendering enabled in the View Layer Properties:

use for rendering

This setting can also be keyframed, let's say you have an animation where you want to use a second view layer to Alpha Over in the Compositor but only for certain frames. Then you can disable it for all other frames where you don't need it.

If you now have let's say 10 view layers and you want to render only one of them, you do not need to disable 9, in this case you can enable Render Single Layer and only this view layer will be rendered.

But: you can still use the other 9 layers in the Compositor, when they have been rendered before - Blender will used a cached render of those layers.

This can be useful if your 9 layers create a background image which does not change, and the one layer you set to Render Single Layer has an animation which you want to lay over the others.

Sidenote: the option Render Single Layer stays enabled when switching to a different view layer. This means, always the active view layer will be single-rendered.

More sidenotes: If you have both view layers in the Compositor and made changes on only one of them, you don't have to set Render Single Layer and press F12 to re-render that one layer where you have made changes when you want to keep the other without re-rendering. In the Compositor, you can just click on the Render button next to the view layer's name in the Render Layers node to re-render that single layer.

Last but not least: When you press F12 to render a scene and both view layers get rendered even though you have only one in a Render Layers node in the Compositor, you can add another Render Layers node and switch it to the second view layer and it will be used for compositing without having to render again because it had been rendered before.


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